diff --git a/aws/resource_aws_dx_gateway_association.go b/aws/resource_aws_dx_gateway_association.go
index 36fa5f4b3e6..88909978f0d 100644
--- a/aws/resource_aws_dx_gateway_association.go
+++ b/aws/resource_aws_dx_gateway_association.go
@@ -1,6 +1,7 @@
 package aws
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"strings"
@@ -34,22 +35,58 @@ func resourceAwsDxGatewayAssociation() *schema.Resource {
 				Elem:     &schema.Schema{Type: schema.TypeString},
 			},
 
-			"dx_gateway_id": {
+			"associated_gateway_id": {
+				Type:          schema.TypeString,
+				Optional:      true,
+				Computed:      true,
+				ForceNew:      true,
+				ConflictsWith: []string{"associated_gateway_owner_account_id", "proposal_id", "vpn_gateway_id"},
+			},
+
+			"associated_gateway_owner_account_id": {
+				Type:          schema.TypeString,
+				Optional:      true,
+				Computed:      true,
+				ForceNew:      true,
+				ValidateFunc:  validateAwsAccountId,
+				ConflictsWith: []string{"associated_gateway_id", "vpn_gateway_id"},
+			},
+
+			"associated_gateway_type": {
 				Type:     schema.TypeString,
-				Required: true,
-				ForceNew: true,
+				Computed: true,
 			},
 
-			"vpn_gateway_id": {
+			"dx_gateway_association_id": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+
+			"dx_gateway_id": {
 				Type:     schema.TypeString,
 				Required: true,
 				ForceNew: true,
 			},
 
-			"dx_gateway_association_id": {
+			"dx_gateway_owner_account_id": {
 				Type:     schema.TypeString,
 				Computed: true,
 			},
+
+			"proposal_id": {
+				Type:          schema.TypeString,
+				Optional:      true,
+				ForceNew:      true,
+				ConflictsWith: []string{"associated_gateway_id", "vpn_gateway_id"},
+			},
+
+			"vpn_gateway_id": {
+				Type:          schema.TypeString,
+				Optional:      true,
+				ForceNew:      true,
+				ConflictsWith: []string{"associated_gateway_id", "associated_gateway_owner_account_id", "proposal_id"},
+				Deprecated:    "use 'associated_gateway_id' argument instead",
+			},
 		},
 
 		Timeouts: &schema.ResourceTimeout{
@@ -64,31 +101,65 @@ func resourceAwsDxGatewayAssociationCreate(d *schema.ResourceData, meta interfac
 	conn := meta.(*AWSClient).dxconn
 
 	dxgwId := d.Get("dx_gateway_id").(string)
-	vgwId := d.Get("vpn_gateway_id").(string)
-	req := &directconnect.CreateDirectConnectGatewayAssociationInput{
-		AddAllowedPrefixesToDirectConnectGateway: expandDxRouteFilterPrefixes(d.Get("allowed_prefixes").(*schema.Set)),
-		DirectConnectGatewayId:                   aws.String(dxgwId),
-		VirtualGatewayId:                         aws.String(vgwId),
+	gwIdRaw, gwIdOk := d.GetOk("associated_gateway_id")
+	vgwIdRaw, vgwIdOk := d.GetOk("vpn_gateway_id")
+	gwAcctIdRaw, gwAcctIdOk := d.GetOk("associated_gateway_owner_account_id")
+	proposalIdRaw, proposalIdOk := d.GetOk("proposal_id")
+
+	if gwAcctIdOk || proposalIdOk {
+		// Cross-account association.
+		if !(gwAcctIdOk && proposalIdOk) {
+			return fmt.Errorf("associated_gateway_owner_account_id and proposal_id must be configured")
+		}
+	} else if !(gwIdOk || vgwIdOk) {
+		return fmt.Errorf("either associated_gateway_owner_account_id and proposal_id or one of associated_gateway_id or vpn_gateway_id must be configured")
 	}
 
-	log.Printf("[DEBUG] Creating Direct Connect gateway association: %#v", req)
-	_, err := conn.CreateDirectConnectGatewayAssociation(req)
-	if err != nil {
-		return fmt.Errorf("error creating Direct Connect gateway association: %s", err)
-	}
+	associationId := ""
+	if gwAcctIdOk {
+		req := &directconnect.AcceptDirectConnectGatewayAssociationProposalInput{
+			AssociatedGatewayOwnerAccount:                 aws.String(gwAcctIdRaw.(string)),
+			DirectConnectGatewayId:                        aws.String(dxgwId),
+			OverrideAllowedPrefixesToDirectConnectGateway: expandDxRouteFilterPrefixes(d.Get("allowed_prefixes").(*schema.Set)),
+			ProposalId: aws.String(proposalIdRaw.(string)),
+		}
 
-	d.SetId(dxGatewayAssociationId(dxgwId, vgwId))
+		log.Printf("[DEBUG] Accepting Direct Connect gateway association proposal: %#v", req)
+		resp, err := conn.AcceptDirectConnectGatewayAssociationProposal(req)
+		if err != nil {
+			return fmt.Errorf("error accepting Direct Connect gateway association proposal: %s", err)
+		}
 
-	stateConf := &resource.StateChangeConf{
-		Pending:    []string{directconnect.GatewayAssociationStateAssociating},
-		Target:     []string{directconnect.GatewayAssociationStateAssociated},
-		Refresh:    dxGatewayAssociationStateRefresh(conn, dxgwId, vgwId),
-		Timeout:    d.Timeout(schema.TimeoutCreate),
-		Delay:      10 * time.Second,
-		MinTimeout: 5 * time.Second,
+		// For historical reasons the resource ID isn't set to the association ID returned from the API.
+		associationId = aws.StringValue(resp.DirectConnectGatewayAssociation.AssociationId)
+		d.SetId(dxGatewayAssociationId(dxgwId, aws.StringValue(resp.DirectConnectGatewayAssociation.AssociatedGateway.Id)))
+	} else {
+		req := &directconnect.CreateDirectConnectGatewayAssociationInput{
+			AddAllowedPrefixesToDirectConnectGateway: expandDxRouteFilterPrefixes(d.Get("allowed_prefixes").(*schema.Set)),
+			DirectConnectGatewayId:                   aws.String(dxgwId),
+		}
+		gwId := ""
+		if gwIdOk {
+			gwId = gwIdRaw.(string)
+			req.GatewayId = aws.String(gwId)
+		} else {
+			gwId = vgwIdRaw.(string)
+			req.VirtualGatewayId = aws.String(gwId)
+		}
+
+		log.Printf("[DEBUG] Creating Direct Connect gateway association: %#v", req)
+		resp, err := conn.CreateDirectConnectGatewayAssociation(req)
+		if err != nil {
+			return fmt.Errorf("error creating Direct Connect gateway association: %s", err)
+		}
+
+		// For historical reasons the resource ID isn't set to the association ID returned from the API.
+		associationId = aws.StringValue(resp.DirectConnectGatewayAssociation.AssociationId)
+		d.SetId(dxGatewayAssociationId(dxgwId, gwId))
 	}
-	_, err = stateConf.WaitForState()
-	if err != nil {
+	d.Set("dx_gateway_association_id", associationId)
+
+	if err := waitForDirectConnectGatewayAssociationAvailabilityOnCreate(conn, associationId, d.Timeout(schema.TimeoutCreate)); err != nil {
 		return fmt.Errorf("error waiting for Direct Connect gateway association (%s) to become available: %s", d.Id(), err)
 	}
 
@@ -98,11 +169,10 @@ func resourceAwsDxGatewayAssociationCreate(d *schema.ResourceData, meta interfac
 func resourceAwsDxGatewayAssociationRead(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).dxconn
 
-	dxgwId := d.Get("dx_gateway_id").(string)
-	vgwId := d.Get("vpn_gateway_id").(string)
-	assocRaw, state, err := dxGatewayAssociationStateRefresh(conn, dxgwId, vgwId)()
+	associationId := d.Get("dx_gateway_association_id").(string)
+	assocRaw, state, err := dxGatewayAssociationStateRefresh(conn, associationId)()
 	if err != nil {
-		return fmt.Errorf("error reading Direct Connect gateway association: %s", err)
+		return fmt.Errorf("error reading Direct Connect gateway association (%s): %s", d.Id(), err)
 	}
 	if state == gatewayAssociationStateDeleted {
 		log.Printf("[WARN] Direct Connect gateway association (%s) not found, removing from state", d.Id())
@@ -111,24 +181,38 @@ func resourceAwsDxGatewayAssociationRead(d *schema.ResourceData, meta interface{
 	}
 
 	assoc := assocRaw.(*directconnect.GatewayAssociation)
-	d.Set("dx_gateway_id", assoc.DirectConnectGatewayId)
-	d.Set("vpn_gateway_id", assoc.VirtualGatewayId)
-	d.Set("dx_gateway_association_id", assoc.AssociationId)
+
 	err = d.Set("allowed_prefixes", flattenDxRouteFilterPrefixes(assoc.AllowedPrefixesToDirectConnectGateway))
 	if err != nil {
 		return fmt.Errorf("error setting allowed_prefixes: %s", err)
 	}
 
+	if _, ok := d.GetOk("vpn_gateway_id"); ok {
+		d.Set("vpn_gateway_id", assoc.VirtualGatewayId)
+	} else {
+		d.Set("associated_gateway_id", assoc.AssociatedGateway.Id)
+	}
+	d.Set("associated_gateway_owner_account_id", assoc.AssociatedGateway.OwnerAccount)
+	d.Set("associated_gateway_type", assoc.AssociatedGateway.Type)
+	d.Set("dx_gateway_association_id", assoc.AssociationId)
+	d.Set("dx_gateway_id", assoc.DirectConnectGatewayId)
+	d.Set("dx_gateway_owner_account_id", assoc.DirectConnectGatewayOwnerAccount)
+
 	return nil
 }
 
 func resourceAwsDxGatewayAssociationUpdate(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).dxconn
 
-	dxgwId := d.Get("dx_gateway_id").(string)
-	vgwId := d.Get("vpn_gateway_id").(string)
+	_, gwIdOk := d.GetOk("associated_gateway_id")
+	_, vgwIdOk := d.GetOk("vpn_gateway_id")
+	if !gwIdOk && !vgwIdOk {
+		return errors.New("one of associated_gateway_id or vpn_gateway_id must be configured")
+	}
 
 	if d.HasChange("allowed_prefixes") {
+		associationId := d.Get("dx_gateway_association_id").(string)
+
 		oraw, nraw := d.GetChange("allowed_prefixes")
 		o := oraw.(*schema.Set)
 		n := nraw.(*schema.Set)
@@ -137,26 +221,17 @@ func resourceAwsDxGatewayAssociationUpdate(d *schema.ResourceData, meta interfac
 
 		req := &directconnect.UpdateDirectConnectGatewayAssociationInput{
 			AddAllowedPrefixesToDirectConnectGateway:    expandDxRouteFilterPrefixes(add),
-			AssociationId:                               aws.String(d.Get("dx_gateway_association_id").(string)),
+			AssociationId:                               aws.String(associationId),
 			RemoveAllowedPrefixesToDirectConnectGateway: expandDxRouteFilterPrefixes(del),
 		}
 
-		log.Printf("[DEBUG] Direct Connect gateway association: %#v", req)
+		log.Printf("[DEBUG] Updating Direct Connect gateway association: %#v", req)
 		_, err := conn.UpdateDirectConnectGatewayAssociation(req)
 		if err != nil {
 			return fmt.Errorf("error updating Direct Connect gateway association (%s): %s", d.Id(), err)
 		}
 
-		stateConf := &resource.StateChangeConf{
-			Pending:    []string{directconnect.GatewayAssociationStateUpdating},
-			Target:     []string{directconnect.GatewayAssociationStateAssociated},
-			Refresh:    dxGatewayAssociationStateRefresh(conn, dxgwId, vgwId),
-			Timeout:    d.Timeout(schema.TimeoutUpdate),
-			Delay:      10 * time.Second,
-			MinTimeout: 5 * time.Second,
-		}
-		_, err = stateConf.WaitForState()
-		if err != nil {
+		if err := waitForDirectConnectGatewayAssociationAvailabilityOnUpdate(conn, associationId, d.Timeout(schema.TimeoutUpdate)); err != nil {
 			return fmt.Errorf("error waiting for Direct Connect gateway association (%s) to become available: %s", d.Id(), err)
 		}
 	}
@@ -167,13 +242,11 @@ func resourceAwsDxGatewayAssociationUpdate(d *schema.ResourceData, meta interfac
 func resourceAwsDxGatewayAssociationDelete(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).dxconn
 
-	dxgwId := d.Get("dx_gateway_id").(string)
-	vgwId := d.Get("vpn_gateway_id").(string)
+	associationId := d.Get("dx_gateway_association_id").(string)
 
 	log.Printf("[DEBUG] Deleting Direct Connect gateway association: %s", d.Id())
 	_, err := conn.DeleteDirectConnectGatewayAssociation(&directconnect.DeleteDirectConnectGatewayAssociationInput{
-		DirectConnectGatewayId: aws.String(dxgwId),
-		VirtualGatewayId:       aws.String(vgwId),
+		AssociationId: aws.String(associationId),
 	})
 	if isAWSErr(err, directconnect.ErrCodeClientException, "No association exists") {
 		return nil
@@ -182,8 +255,8 @@ func resourceAwsDxGatewayAssociationDelete(d *schema.ResourceData, meta interfac
 		return fmt.Errorf("error deleting Direct Connect gateway association: %s", err)
 	}
 
-	if err := waitForDirectConnectGatewayAssociationDeletion(conn, dxgwId, vgwId, d.Timeout(schema.TimeoutDelete)); err != nil {
-		return fmt.Errorf("error waiting for Direct Connect gateway association (%s) to be deleted: %s", d.Id(), err.Error())
+	if err := waitForDirectConnectGatewayAssociationDeletion(conn, associationId, d.Timeout(schema.TimeoutDelete)); err != nil {
+		return fmt.Errorf("error waiting for Direct Connect gateway association (%s) to be deleted: %s", d.Id(), err)
 	}
 
 	return nil
@@ -192,25 +265,38 @@ func resourceAwsDxGatewayAssociationDelete(d *schema.ResourceData, meta interfac
 func resourceAwsDxGatewayAssociationImport(d *schema.ResourceData, meta interface{}) ([]*schema.ResourceData, error) {
 	parts := strings.Split(d.Id(), "/")
 	if len(parts) != 2 {
-		return []*schema.ResourceData{}, fmt.Errorf("Wrong format of resource: %s. Please follow 'dx-gw-id/vgw-id'", d.Id())
+		return []*schema.ResourceData{}, fmt.Errorf("Wrong format of resource: %s. Please follow 'dx-gw-id/gw-id'", d.Id())
 	}
 
 	dxgwId := parts[0]
-	vgwId := parts[1]
-	log.Printf("[DEBUG] Importing Direct Connect gateway association %s/%s", dxgwId, vgwId)
+	gwId := parts[1]
+	id := dxGatewayAssociationId(dxgwId, gwId)
+	log.Printf("[DEBUG] Importing Direct Connect gateway association %s/%s", dxgwId, gwId)
 
-	d.SetId(dxGatewayAssociationId(dxgwId, vgwId))
-	d.Set("dx_gateway_id", dxgwId)
-	d.Set("vpn_gateway_id", vgwId)
+	conn := meta.(*AWSClient).dxconn
+
+	resp, err := conn.DescribeDirectConnectGatewayAssociations(&directconnect.DescribeDirectConnectGatewayAssociationsInput{
+		AssociatedGatewayId:    aws.String(gwId),
+		DirectConnectGatewayId: aws.String(dxgwId),
+	})
+	if err != nil {
+		return nil, err
+	}
+	if n := len(resp.DirectConnectGatewayAssociations); n != 1 {
+		return nil, fmt.Errorf("Found %d Direct Connect gateway associations for %s, expected 1", n, id)
+	}
+
+	d.SetId(id)
+	d.Set("dx_gateway_id", resp.DirectConnectGatewayAssociations[0].DirectConnectGatewayId)
+	d.Set("dx_gateway_association_id", resp.DirectConnectGatewayAssociations[0].AssociationId)
 
 	return []*schema.ResourceData{d}, nil
 }
 
-func dxGatewayAssociationStateRefresh(conn *directconnect.DirectConnect, dxgwId, vgwId string) resource.StateRefreshFunc {
+func dxGatewayAssociationStateRefresh(conn *directconnect.DirectConnect, associationId string) resource.StateRefreshFunc {
 	return func() (interface{}, string, error) {
 		resp, err := conn.DescribeDirectConnectGatewayAssociations(&directconnect.DescribeDirectConnectGatewayAssociationsInput{
-			DirectConnectGatewayId: aws.String(dxgwId),
-			VirtualGatewayId:       aws.String(vgwId),
+			AssociationId: aws.String(associationId),
 		})
 		if err != nil {
 			return nil, "", err
@@ -223,23 +309,62 @@ func dxGatewayAssociationStateRefresh(conn *directconnect.DirectConnect, dxgwId,
 
 		case 1:
 			assoc := resp.DirectConnectGatewayAssociations[0]
+
+			if stateChangeError := aws.StringValue(assoc.StateChangeError); stateChangeError != "" {
+				id := dxGatewayAssociationId(
+					aws.StringValue(resp.DirectConnectGatewayAssociations[0].DirectConnectGatewayId),
+					aws.StringValue(resp.DirectConnectGatewayAssociations[0].AssociatedGateway.Id))
+				log.Printf("[INFO] Direct Connect gateway association (%s) state change error: %s", id, stateChangeError)
+			}
+
 			return assoc, aws.StringValue(assoc.AssociationState), nil
 
 		default:
-			return nil, "", fmt.Errorf("Found %d Direct Connect gateway associations for %s, expected 1", n, dxGatewayAssociationId(dxgwId, vgwId))
+			return nil, "", fmt.Errorf("Found %d Direct Connect gateway associations for %s, expected 1", n, associationId)
 		}
 	}
 }
 
-func dxGatewayAssociationId(dxgwId, vgwId string) string {
-	return fmt.Sprintf("ga-%s%s", dxgwId, vgwId)
+// Terraform resource ID.
+func dxGatewayAssociationId(dxgwId, gwId string) string {
+	return fmt.Sprintf("ga-%s%s", dxgwId, gwId)
+}
+
+func waitForDirectConnectGatewayAssociationAvailabilityOnCreate(conn *directconnect.DirectConnect, associationId string, timeout time.Duration) error {
+	stateConf := &resource.StateChangeConf{
+		Pending:    []string{directconnect.GatewayAssociationStateAssociating},
+		Target:     []string{directconnect.GatewayAssociationStateAssociated},
+		Refresh:    dxGatewayAssociationStateRefresh(conn, associationId),
+		Timeout:    timeout,
+		Delay:      10 * time.Second,
+		MinTimeout: 5 * time.Second,
+	}
+
+	_, err := stateConf.WaitForState()
+
+	return err
+}
+
+func waitForDirectConnectGatewayAssociationAvailabilityOnUpdate(conn *directconnect.DirectConnect, associationId string, timeout time.Duration) error {
+	stateConf := &resource.StateChangeConf{
+		Pending:    []string{directconnect.GatewayAssociationStateUpdating},
+		Target:     []string{directconnect.GatewayAssociationStateAssociated},
+		Refresh:    dxGatewayAssociationStateRefresh(conn, associationId),
+		Timeout:    timeout,
+		Delay:      10 * time.Second,
+		MinTimeout: 5 * time.Second,
+	}
+
+	_, err := stateConf.WaitForState()
+
+	return err
 }
 
-func waitForDirectConnectGatewayAssociationDeletion(conn *directconnect.DirectConnect, directConnectGatewayID, virtualGatewayID string, timeout time.Duration) error {
+func waitForDirectConnectGatewayAssociationDeletion(conn *directconnect.DirectConnect, associationId string, timeout time.Duration) error {
 	stateConf := &resource.StateChangeConf{
 		Pending:    []string{directconnect.GatewayAssociationStateDisassociating},
 		Target:     []string{directconnect.GatewayAssociationStateDisassociated, gatewayAssociationStateDeleted},
-		Refresh:    dxGatewayAssociationStateRefresh(conn, directConnectGatewayID, virtualGatewayID),
+		Refresh:    dxGatewayAssociationStateRefresh(conn, associationId),
 		Timeout:    timeout,
 		Delay:      10 * time.Second,
 		MinTimeout: 5 * time.Second,
diff --git a/aws/resource_aws_dx_gateway_association_proposal.go b/aws/resource_aws_dx_gateway_association_proposal.go
index 6bd3d3d3642..49f2522a8c1 100644
--- a/aws/resource_aws_dx_gateway_association_proposal.go
+++ b/aws/resource_aws_dx_gateway_association_proposal.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/directconnect"
+	"github.com/hashicorp/terraform/helper/customdiff"
 	"github.com/hashicorp/terraform/helper/schema"
 )
 
@@ -18,14 +19,43 @@ func resourceAwsDxGatewayAssociationProposal() *schema.Resource {
 			State: schema.ImportStatePassthrough,
 		},
 
+		CustomizeDiff: customdiff.Sequence(
+			// Accepting the proposal with overridden prefixes changes the returned RequestedAllowedPrefixesToDirectConnectGateway value (allowed_prefixes attribute).
+			// We only want to force a new resource if this value changes and the current proposal state is "requested".
+			customdiff.ForceNewIf("allowed_prefixes", func(d *schema.ResourceDiff, meta interface{}) bool {
+				conn := meta.(*AWSClient).dxconn
+
+				proposal, err := describeDirectConnectGatewayAssociationProposal(conn, d.Id())
+				if err != nil {
+					log.Printf("[ERROR] Error reading Direct Connect Gateway Association Proposal (%s): %s", d.Id(), err)
+					return false
+				}
+
+				return proposal != nil && aws.StringValue(proposal.ProposalState) == directconnect.GatewayAssociationProposalStateRequested
+			}),
+		),
+
 		Schema: map[string]*schema.Schema{
 			"allowed_prefixes": {
 				Type:     schema.TypeSet,
 				Optional: true,
 				Computed: true,
-				ForceNew: true,
 				Elem:     &schema.Schema{Type: schema.TypeString},
 			},
+			"associated_gateway_id": {
+				Type:          schema.TypeString,
+				Optional:      true,
+				ForceNew:      true,
+				ConflictsWith: []string{"vpn_gateway_id"},
+			},
+			"associated_gateway_owner_account_id": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+			"associated_gateway_type": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
 			"dx_gateway_id": {
 				Type:     schema.TypeString,
 				Required: true,
@@ -38,9 +68,11 @@ func resourceAwsDxGatewayAssociationProposal() *schema.Resource {
 				ValidateFunc: validateAwsAccountId,
 			},
 			"vpn_gateway_id": {
-				Type:     schema.TypeString,
-				Required: true,
-				ForceNew: true,
+				Type:          schema.TypeString,
+				Optional:      true,
+				ForceNew:      true,
+				ConflictsWith: []string{"associated_gateway_id"},
+				Deprecated:    "use 'associated_gateway_id' argument instead",
 			},
 		},
 	}
@@ -49,13 +81,25 @@ func resourceAwsDxGatewayAssociationProposal() *schema.Resource {
 func resourceAwsDxGatewayAssociationProposalCreate(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).dxconn
 
+	allowedPrefixes := expandDirectConnectGatewayAssociationProposalAllowedPrefixes(d.Get("allowed_prefixes").(*schema.Set).List())
 	input := &directconnect.CreateDirectConnectGatewayAssociationProposalInput{
-		AddAllowedPrefixesToDirectConnectGateway: expandDirectConnectGatewayAssociationProposalAllowedPrefixes(d.Get("allowed_prefixes").(*schema.Set).List()),
+		AddAllowedPrefixesToDirectConnectGateway: allowedPrefixes,
 		DirectConnectGatewayId:                   aws.String(d.Get("dx_gateway_id").(string)),
 		DirectConnectGatewayOwnerAccount:         aws.String(d.Get("dx_gateway_owner_account_id").(string)),
-		GatewayId:                                aws.String(d.Get("vpn_gateway_id").(string)),
+	}
+	var gwID string
+	if v, ok := d.GetOk("vpn_gateway_id"); ok {
+		gwID = v.(string)
+	} else if v, ok := d.GetOk("associated_gateway_id"); ok {
+		gwID = v.(string)
 	}
 
+	if gwID == "" {
+		return fmt.Errorf("gateway id not provided, one of associated_gateway_id or vpn_gateway_id must be configured")
+	}
+
+	input.GatewayId = aws.String(gwID)
+
 	log.Printf("[DEBUG] Creating Direct Connect Gateway Association Proposal: %s", input)
 	output, err := conn.CreateDirectConnectGatewayAssociationProposal(input)
 
@@ -97,9 +141,15 @@ func resourceAwsDxGatewayAssociationProposalRead(d *schema.ResourceData, meta in
 		return fmt.Errorf("error setting allowed_prefixes: %s", err)
 	}
 
+	if _, ok := d.GetOk("vpn_gateway_id"); ok {
+		d.Set("vpn_gateway_id", aws.StringValue(proposal.AssociatedGateway.Id))
+	} else {
+		d.Set("associated_gateway_id", aws.StringValue(proposal.AssociatedGateway.Id))
+	}
+	d.Set("associated_gateway_owner_account_id", proposal.AssociatedGateway.OwnerAccount)
+	d.Set("associated_gateway_type", proposal.AssociatedGateway.Type)
 	d.Set("dx_gateway_id", aws.StringValue(proposal.DirectConnectGatewayId))
 	d.Set("dx_gateway_owner_account_id", aws.StringValue(proposal.DirectConnectGatewayOwnerAccount))
-	d.Set("vpn_gateway_id", aws.StringValue(proposal.AssociatedGateway.Id))
 
 	return nil
 }
diff --git a/aws/resource_aws_dx_gateway_association_proposal_test.go b/aws/resource_aws_dx_gateway_association_proposal_test.go
index 4cb2ffa6bfa..6c77d874e56 100644
--- a/aws/resource_aws_dx_gateway_association_proposal_test.go
+++ b/aws/resource_aws_dx_gateway_association_proposal_test.go
@@ -12,12 +12,14 @@ import (
 	"github.com/hashicorp/terraform/terraform"
 )
 
-func TestAccAwsDxGatewayAssociationProposal_basic(t *testing.T) {
+func TestAccAwsDxGatewayAssociationProposal_VpnGatewayId(t *testing.T) {
 	var proposal1 directconnect.GatewayAssociationProposal
 	var providers []*schema.Provider
 	rBgpAsn := randIntRange(64512, 65534)
 	rName := acctest.RandomWithPrefix("tf-acc-test")
 	resourceName := "aws_dx_gateway_association_proposal.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameVgw := "aws_vpn_gateway.test"
 
 	resource.ParallelTest(t, resource.TestCase{
 		PreCheck: func() {
@@ -28,14 +30,93 @@ func TestAccAwsDxGatewayAssociationProposal_basic(t *testing.T) {
 		CheckDestroy:      testAccCheckAwsDxGatewayAssociationProposalDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccDxGatewayAssociationProposalConfig(rName, rBgpAsn),
+				Config: testAccDxGatewayAssociationProposalConfig_vpnGatewayId(rName, rBgpAsn),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAwsDxGatewayAssociationProposalExists(resourceName, &proposal1),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "vpn_gateway_id", resourceNameVgw, "id"),
+					resource.TestCheckNoResourceAttr(resourceName, "associated_gateway_id"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "virtualPrivateGateway"),
 					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "1"),
 				),
 			},
+		},
+	})
+}
+
+func TestAccAwsDxGatewayAssociationProposal_basicVpnGateway(t *testing.T) {
+	var proposal1 directconnect.GatewayAssociationProposal
+	var providers []*schema.Provider
+	rBgpAsn := randIntRange(64512, 65534)
+	rName := acctest.RandomWithPrefix("tf-acc-test")
+	resourceName := "aws_dx_gateway_association_proposal.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameVgw := "aws_vpn_gateway.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck: func() {
+			testAccPreCheck(t)
+			testAccAlternateAccountPreCheck(t)
+		},
+		ProviderFactories: testAccProviderFactories(&providers),
+		CheckDestroy:      testAccCheckAwsDxGatewayAssociationProposalDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccDxGatewayAssociationProposalConfig_basicVpnGateway(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationProposalExists(resourceName, &proposal1),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameVgw, "id"),
+					resource.TestCheckNoResourceAttr(resourceName, "vpn_gateway_id"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "virtualPrivateGateway"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "1"),
+				),
+			},
+			{
+				Config:            testAccDxGatewayAssociationProposalConfig_basicVpnGateway(rName, rBgpAsn),
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
+func TestAccAwsDxGatewayAssociationProposal_basicTransitGateway(t *testing.T) {
+	var proposal1 directconnect.GatewayAssociationProposal
+	var providers []*schema.Provider
+	rBgpAsn := randIntRange(64512, 65534)
+	rName := acctest.RandomWithPrefix("tf-acc-test")
+	resourceName := "aws_dx_gateway_association_proposal.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameTgw := "aws_ec2_transit_gateway.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck: func() {
+			testAccPreCheck(t)
+			testAccAlternateAccountPreCheck(t)
+		},
+		ProviderFactories: testAccProviderFactories(&providers),
+		CheckDestroy:      testAccCheckAwsDxGatewayAssociationProposalDestroy,
+		Steps: []resource.TestStep{
 			{
-				Config:            testAccDxGatewayAssociationProposalConfig(rName, rBgpAsn),
+				Config: testAccDxGatewayAssociationProposalConfig_basicTransitGateway(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationProposalExists(resourceName, &proposal1),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameTgw, "id"),
+					resource.TestCheckNoResourceAttr(resourceName, "vpn_gateway_id"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "transitGateway"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "2"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2173830893", "10.255.255.0/30"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2984398124", "10.255.255.8/30"),
+				),
+			},
+			{
+				Config:            testAccDxGatewayAssociationProposalConfig_basicVpnGateway(rName, rBgpAsn),
 				ResourceName:      resourceName,
 				ImportState:       true,
 				ImportStateVerify: true,
@@ -60,7 +141,7 @@ func TestAccAwsDxGatewayAssociationProposal_disappears(t *testing.T) {
 		CheckDestroy:      testAccCheckAwsDxGatewayAssociationProposalDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccDxGatewayAssociationProposalConfig(rName, rBgpAsn),
+				Config: testAccDxGatewayAssociationProposalConfig_basicVpnGateway(rName, rBgpAsn),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAwsDxGatewayAssociationProposalExists(resourceName, &proposal1),
 					testAccCheckAwsDxGatewayAssociationProposalDisappears(&proposal1),
@@ -184,7 +265,7 @@ func testAccCheckAwsDxGatewayAssociationProposalRecreated(i, j *directconnect.Ga
 	}
 }
 
-func testAccDxGatewayAssociationProposalConfigBase(rName string, rBgpAsn int) string {
+func testAccDxGatewayAssociationProposalConfigBase_vpnGateway(rName string, rBgpAsn int) string {
 	return testAccAlternateAccountProviderConfig() + fmt.Sprintf(`
 resource "aws_dx_gateway" "test" {
   provider = "aws.alternate"
@@ -197,7 +278,7 @@ resource "aws_vpc" "test" {
   cidr_block = "10.0.0.0/16"
 
   tags = {
-    Name = "tf-acc-test-dx-gateway-association-proposal"
+    Name = %[1]q
   }
 }
 
@@ -205,14 +286,14 @@ resource "aws_vpn_gateway" "test" {
   vpc_id = "${aws_vpc.test.id}"
 
   tags = {
-    Name = "tf-acc-test-dx-gateway-association-proposal"
+    Name = %[1]q
   }
 }
 `, rName, rBgpAsn)
 }
 
-func testAccDxGatewayAssociationProposalConfig(rName string, rBgpAsn int) string {
-	return testAccDxGatewayAssociationProposalConfigBase(rName, rBgpAsn) + fmt.Sprintf(`
+func testAccDxGatewayAssociationProposalConfig_vpnGatewayId(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationProposalConfigBase_vpnGateway(rName, rBgpAsn) + fmt.Sprintf(`
 resource "aws_dx_gateway_association_proposal" "test" {
   dx_gateway_id               = "${aws_dx_gateway.test.id}"
   dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
@@ -221,24 +302,62 @@ resource "aws_dx_gateway_association_proposal" "test" {
 `)
 }
 
+func testAccDxGatewayAssociationProposalConfig_basicVpnGateway(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationProposalConfigBase_vpnGateway(rName, rBgpAsn) + fmt.Sprintf(`
+resource "aws_dx_gateway_association_proposal" "test" {
+  dx_gateway_id               = "${aws_dx_gateway.test.id}"
+  dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
+  associated_gateway_id       = "${aws_vpn_gateway.test.id}"
+}
+`)
+}
+
+func testAccDxGatewayAssociationProposalConfig_basicTransitGateway(rName string, rBgpAsn int) string {
+	return testAccAlternateAccountProviderConfig() + fmt.Sprintf(`
+resource "aws_dx_gateway" "test" {
+  provider = "aws.alternate"
+
+  amazon_side_asn = %[2]d
+  name            = %[1]q
+}
+
+resource "aws_ec2_transit_gateway" "test" {
+  tags = {
+    Name = %[1]q
+  }
+}
+
+resource "aws_dx_gateway_association_proposal" "test" {
+  dx_gateway_id               = "${aws_dx_gateway.test.id}"
+  dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
+  associated_gateway_id       = "${aws_ec2_transit_gateway.test.id}"
+
+  allowed_prefixes = [
+    "10.255.255.0/30",
+    "10.255.255.8/30",
+  ]
+}
+`, rName, rBgpAsn)
+}
+
 func testAccDxGatewayAssociationProposalConfigAllowedPrefixes1(rName string, rBgpAsn int) string {
-	return testAccDxGatewayAssociationProposalConfigBase(rName, rBgpAsn) + fmt.Sprintf(`
+	return testAccDxGatewayAssociationProposalConfigBase_vpnGateway(rName, rBgpAsn) + fmt.Sprintf(`
 resource "aws_dx_gateway_association_proposal" "test" {
   allowed_prefixes            = ["10.0.0.0/16"]
   dx_gateway_id               = "${aws_dx_gateway.test.id}"
   dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
-  vpn_gateway_id              = "${aws_vpn_gateway.test.id}"
+  associated_gateway_id       = "${aws_vpn_gateway.test.id}"
 }
 `)
 }
 
 func testAccDxGatewayAssociationProposalConfigAllowedPrefixes2(rName string, rBgpAsn int) string {
-	return testAccDxGatewayAssociationProposalConfigBase(rName, rBgpAsn) + fmt.Sprintf(`
+	return testAccDxGatewayAssociationProposalConfigBase_vpnGateway(rName, rBgpAsn) + fmt.Sprintf(`
 resource "aws_dx_gateway_association_proposal" "test" {
   allowed_prefixes            = ["10.0.0.0/24", "10.0.1.0/24"]
   dx_gateway_id               = "${aws_dx_gateway.test.id}"
   dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
-  vpn_gateway_id              = "${aws_vpn_gateway.test.id}"
+  associated_gateway_id       = "${aws_vpn_gateway.test.id}"
 }
 `)
 }
diff --git a/aws/resource_aws_dx_gateway_association_test.go b/aws/resource_aws_dx_gateway_association_test.go
index 9d9af3e6b81..5705530f331 100644
--- a/aws/resource_aws_dx_gateway_association_test.go
+++ b/aws/resource_aws_dx_gateway_association_test.go
@@ -10,6 +10,7 @@ import (
 	"github.com/aws/aws-sdk-go/service/directconnect"
 	"github.com/hashicorp/terraform/helper/acctest"
 	"github.com/hashicorp/terraform/helper/resource"
+	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 )
 
@@ -55,19 +56,18 @@ func testSweepDirectConnectGatewayAssociations(region string) error {
 				}
 
 				for _, association := range associationOutput.DirectConnectGatewayAssociations {
-					virtualGatewayID := aws.StringValue(association.VirtualGatewayId)
+					gatewayID := aws.StringValue(association.AssociatedGateway.Id)
 
 					if aws.StringValue(association.AssociationState) != directconnect.GatewayAssociationStateAssociated {
-						log.Printf("[INFO] Skipping Direct Connect Gateway (%s) Association in non-available (%s) state: %s", directConnectGatewayID, aws.StringValue(association.AssociationState), virtualGatewayID)
+						log.Printf("[INFO] Skipping Direct Connect Gateway (%s) Association in non-available (%s) state: %s", directConnectGatewayID, aws.StringValue(association.AssociationState), gatewayID)
 						continue
 					}
 
 					input := &directconnect.DeleteDirectConnectGatewayAssociationInput{
-						DirectConnectGatewayId: gateway.DirectConnectGatewayId,
-						VirtualGatewayId:       association.VirtualGatewayId,
+						AssociationId: association.AssociationId,
 					}
 
-					log.Printf("[INFO] Deleting Direct Connect Gateway (%s) Association: %s", directConnectGatewayID, virtualGatewayID)
+					log.Printf("[INFO] Deleting Direct Connect Gateway (%s) Association: %s", directConnectGatewayID, gatewayID)
 					_, err := conn.DeleteDirectConnectGatewayAssociation(input)
 
 					if isAWSErr(err, directconnect.ErrCodeClientException, "No association exists") {
@@ -75,11 +75,11 @@ func testSweepDirectConnectGatewayAssociations(region string) error {
 					}
 
 					if err != nil {
-						return fmt.Errorf("error deleting Direct Connect Gateway (%s) Association (%s): %s", directConnectGatewayID, virtualGatewayID, err)
+						return fmt.Errorf("error deleting Direct Connect Gateway (%s) Association (%s): %s", directConnectGatewayID, gatewayID, err)
 					}
 
-					if err := waitForDirectConnectGatewayAssociationDeletion(conn, directConnectGatewayID, virtualGatewayID, 20*time.Minute); err != nil {
-						return fmt.Errorf("error waiting for Direct Connect Gateway (%s) Association (%s) to be deleted: %s", directConnectGatewayID, virtualGatewayID, err)
+					if err := waitForDirectConnectGatewayAssociationDeletion(conn, aws.StringValue(association.AssociationId), 20*time.Minute); err != nil {
+						return fmt.Errorf("error waiting for Direct Connect Gateway (%s) Association (%s) to be deleted: %s", directConnectGatewayID, gatewayID, err)
 					}
 				}
 
@@ -101,7 +101,7 @@ func testSweepDirectConnectGatewayAssociations(region string) error {
 	return nil
 }
 
-func TestAccAwsDxGatewayAssociation_basic(t *testing.T) {
+func TestAccAwsDxGatewayAssociation_deprecatedSingleAccount(t *testing.T) {
 	resourceName := "aws_dx_gateway_association.test"
 	resourceNameDxGw := "aws_dx_gateway.test"
 	resourceNameVgw := "aws_vpn_gateway.test"
@@ -114,12 +114,47 @@ func TestAccAwsDxGatewayAssociation_basic(t *testing.T) {
 		CheckDestroy: testAccCheckAwsDxGatewayAssociationDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccDxGatewayAssociationConfig_basic(rName, rBgpAsn),
+				Config: testAccDxGatewayAssociationConfig_deprecatedSingleAccount(rName, rBgpAsn),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAwsDxGatewayAssociationExists(resourceName),
 					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
 					resource.TestCheckResourceAttrPair(resourceName, "vpn_gateway_id", resourceNameVgw, "id"),
 					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
+					resource.TestCheckNoResourceAttr(resourceName, "associated_gateway_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "virtualPrivateGateway"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					testAccCheckResourceAttrAccountID(resourceName, "dx_gateway_owner_account_id"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.1216997074", "10.255.255.0/28"),
+				),
+			},
+		},
+	})
+}
+
+func TestAccAwsDxGatewayAssociation_basicVpnGatewaySingleAccount(t *testing.T) {
+	resourceName := "aws_dx_gateway_association.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameVgw := "aws_vpn_gateway.test"
+	rName := fmt.Sprintf("terraform-testacc-dxgwassoc-%d", acctest.RandInt())
+	rBgpAsn := randIntRange(64512, 65534)
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAwsDxGatewayAssociationDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccDxGatewayAssociationConfig_basicVpnGatewaySingleAccount(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationExists(resourceName),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameVgw, "id"),
+					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
+					resource.TestCheckNoResourceAttr(resourceName, "vpn_gateway_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "virtualPrivateGateway"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					testAccCheckResourceAttrAccountID(resourceName, "dx_gateway_owner_account_id"),
 					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "1"),
 					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.1216997074", "10.255.255.0/28"),
 				),
@@ -132,7 +167,7 @@ func TestAccAwsDxGatewayAssociation_basic(t *testing.T) {
 						return "", fmt.Errorf("Not Found: %s", resourceName)
 					}
 
-					return fmt.Sprintf("%s/%s", rs.Primary.Attributes["dx_gateway_id"], rs.Primary.Attributes["vpn_gateway_id"]), nil
+					return fmt.Sprintf("%s/%s", rs.Primary.Attributes["dx_gateway_id"], rs.Primary.Attributes["associated_gateway_id"]), nil
 				},
 				ImportState:       true,
 				ImportStateVerify: true,
@@ -141,7 +176,125 @@ func TestAccAwsDxGatewayAssociation_basic(t *testing.T) {
 	})
 }
 
-func TestAccAwsDxGatewayAssociation_multiVgws(t *testing.T) {
+func TestAccAwsDxGatewayAssociation_basicVpnGatewayCrossAccount(t *testing.T) {
+	var providers []*schema.Provider
+	resourceName := "aws_dx_gateway_association.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameVgw := "aws_vpn_gateway.test"
+	rName := fmt.Sprintf("terraform-testacc-dxgwassoc-%d", acctest.RandInt())
+	rBgpAsn := randIntRange(64512, 65534)
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck: func() {
+			testAccPreCheck(t)
+			testAccAlternateAccountPreCheck(t)
+		},
+		ProviderFactories: testAccProviderFactories(&providers),
+		CheckDestroy:      testAccCheckAwsDxGatewayAssociationDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccDxGatewayAssociationConfig_basicVpnGatewayCrossAccount(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationExists(resourceName),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameVgw, "id"),
+					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
+					resource.TestCheckNoResourceAttr(resourceName, "vpn_gateway_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "virtualPrivateGateway"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					// dx_gateway_owner_account_id is the "aws.alternate" provider's account ID.
+					// testAccCheckResourceAttrAccountID(resourceName, "dx_gateway_owner_account_id"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.1216997074", "10.255.255.0/28"),
+				),
+			},
+		},
+	})
+}
+
+func TestAccAwsDxGatewayAssociation_basicTransitGatewaySingleAccount(t *testing.T) {
+	resourceName := "aws_dx_gateway_association.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameTgw := "aws_ec2_transit_gateway.test"
+	rName := fmt.Sprintf("terraform-testacc-dxgwassoc-%d", acctest.RandInt())
+	rBgpAsn := randIntRange(64512, 65534)
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAwsDxGatewayAssociationDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccDxGatewayAssociationConfig_basicTransitGatewaySingleAccount(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationExists(resourceName),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameTgw, "id"),
+					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
+					resource.TestCheckNoResourceAttr(resourceName, "vpn_gateway_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "transitGateway"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					testAccCheckResourceAttrAccountID(resourceName, "dx_gateway_owner_account_id"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "2"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2173830893", "10.255.255.0/30"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2984398124", "10.255.255.8/30"),
+				),
+			},
+			{
+				ResourceName: resourceName,
+				ImportStateIdFunc: func(s *terraform.State) (string, error) {
+					rs, ok := s.RootModule().Resources[resourceName]
+					if !ok {
+						return "", fmt.Errorf("Not Found: %s", resourceName)
+					}
+
+					return fmt.Sprintf("%s/%s", rs.Primary.Attributes["dx_gateway_id"], rs.Primary.Attributes["associated_gateway_id"]), nil
+				},
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
+func TestAccAwsDxGatewayAssociation_basicTransitGatewayCrossAccount(t *testing.T) {
+	var providers []*schema.Provider
+	resourceName := "aws_dx_gateway_association.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameTgw := "aws_ec2_transit_gateway.test"
+	rName := fmt.Sprintf("terraform-testacc-dxgwassoc-%d", acctest.RandInt())
+	rBgpAsn := randIntRange(64512, 65534)
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck: func() {
+			testAccPreCheck(t)
+			testAccAlternateAccountPreCheck(t)
+		},
+		ProviderFactories: testAccProviderFactories(&providers),
+		CheckDestroy:      testAccCheckAwsDxGatewayAssociationDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccDxGatewayAssociationConfig_basicTransitGatewayCrossAccount(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationExists(resourceName),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameTgw, "id"),
+					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
+					resource.TestCheckNoResourceAttr(resourceName, "vpn_gateway_id"),
+					resource.TestCheckResourceAttr(resourceName, "associated_gateway_type", "transitGateway"),
+					testAccCheckResourceAttrAccountID(resourceName, "associated_gateway_owner_account_id"),
+					// dx_gateway_owner_account_id is the "aws.alternate" provider's account ID.
+					// testAccCheckResourceAttrAccountID(resourceName, "dx_gateway_owner_account_id"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "2"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2173830893", "10.255.255.0/30"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2984398124", "10.255.255.8/30"),
+				),
+			},
+		},
+	})
+}
+
+func TestAccAwsDxGatewayAssociation_multiVpnGatewaysSingleAccount(t *testing.T) {
 	resourceName1 := "aws_dx_gateway_association.test1"
 	resourceName2 := "aws_dx_gateway_association.test2"
 	rName1 := fmt.Sprintf("terraform-testacc-dxgwassoc-%d", acctest.RandInt())
@@ -154,7 +307,7 @@ func TestAccAwsDxGatewayAssociation_multiVgws(t *testing.T) {
 		CheckDestroy: testAccCheckAwsDxGatewayAssociationDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccDxGatewayAssociationConfig_multiVgws(rName1, rName2, rBgpAsn),
+				Config: testAccDxGatewayAssociationConfig_multiVpnGatewaysSingleAccount(rName1, rName2, rBgpAsn),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAwsDxGatewayAssociationExists(resourceName1),
 					testAccCheckAwsDxGatewayAssociationExists(resourceName2),
@@ -170,7 +323,7 @@ func TestAccAwsDxGatewayAssociation_multiVgws(t *testing.T) {
 	})
 }
 
-func TestAccAwsDxGatewayAssociation_allowedPrefixes(t *testing.T) {
+func TestAccAwsDxGatewayAssociation_allowedPrefixesVpnGatewaySingleAccount(t *testing.T) {
 	resourceName := "aws_dx_gateway_association.test"
 	resourceNameDxGw := "aws_dx_gateway.test"
 	resourceNameVgw := "aws_vpn_gateway.test"
@@ -183,11 +336,11 @@ func TestAccAwsDxGatewayAssociation_allowedPrefixes(t *testing.T) {
 		CheckDestroy: testAccCheckAwsDxGatewayAssociationDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccDxGatewayAssociationConfig_allowedPrefixes(rName, rBgpAsn),
+				Config: testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewaySingleAccount(rName, rBgpAsn),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAwsDxGatewayAssociationExists(resourceName),
 					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
-					resource.TestCheckResourceAttrPair(resourceName, "vpn_gateway_id", resourceNameVgw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameVgw, "id"),
 					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
 					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "2"),
 					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2173830893", "10.255.255.0/30"),
@@ -195,12 +348,57 @@ func TestAccAwsDxGatewayAssociation_allowedPrefixes(t *testing.T) {
 				),
 			},
 			{
-				Config: testAccDxGatewayAssociationConfig_allowedPrefixesUpdated(rName, rBgpAsn),
+				Config: testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewaySingleAccountUpdated(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationExists(resourceName),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.1642241106", "10.255.255.8/29"),
+				),
+			},
+		},
+	})
+}
+
+func TestAccAwsDxGatewayAssociation_allowedPrefixesVpnGatewayCrossAccount(t *testing.T) {
+	var providers []*schema.Provider
+	resourceName := "aws_dx_gateway_association.test"
+	resourceNameDxGw := "aws_dx_gateway.test"
+	resourceNameVgw := "aws_vpn_gateway.test"
+	rName := fmt.Sprintf("terraform-testacc-dxgwassoc-%d", acctest.RandInt())
+	rBgpAsn := randIntRange(64512, 65534)
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck: func() {
+			testAccPreCheck(t)
+			testAccAlternateAccountPreCheck(t)
+		},
+		ProviderFactories: testAccProviderFactories(&providers),
+		CheckDestroy:      testAccCheckAwsDxGatewayAssociationDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewayCrossAccount(rName, rBgpAsn),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAwsDxGatewayAssociationExists(resourceName),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameVgw, "id"),
+					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
 					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "1"),
 					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.1642241106", "10.255.255.8/29"),
 				),
+				// Accepting the proposal with overridden prefixes changes the returned RequestedAllowedPrefixesToDirectConnectGateway value (allowed_prefixes attribute).
+				ExpectNonEmptyPlan: true,
+			},
+			{
+				Config: testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewayCrossAccountUpdated(rName, rBgpAsn),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsDxGatewayAssociationExists(resourceName),
+					resource.TestCheckResourceAttrPair(resourceName, "dx_gateway_id", resourceNameDxGw, "id"),
+					resource.TestCheckResourceAttrPair(resourceName, "associated_gateway_id", resourceNameVgw, "id"),
+					resource.TestCheckResourceAttrSet(resourceName, "dx_gateway_association_id"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.#", "2"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2173830893", "10.255.255.0/30"),
+					resource.TestCheckResourceAttr(resourceName, "allowed_prefixes.2984398124", "10.255.255.8/30"),
+				),
 			},
 		},
 	})
@@ -214,13 +412,17 @@ func testAccCheckAwsDxGatewayAssociationDestroy(s *terraform.State) error {
 			continue
 		}
 
-		resp, _ := conn.DescribeDirectConnectGatewayAssociations(&directconnect.DescribeDirectConnectGatewayAssociationsInput{
-			DirectConnectGatewayId: aws.String(rs.Primary.Attributes["dx_gateway_id"]),
-			VirtualGatewayId:       aws.String(rs.Primary.Attributes["vpn_gateway_id"]),
+		resp, err := conn.DescribeDirectConnectGatewayAssociations(&directconnect.DescribeDirectConnectGatewayAssociationsInput{
+			AssociationId: aws.String(rs.Primary.Attributes["dx_gateway_association_id"]),
 		})
+		if err != nil {
+			return err
+		}
 
 		if len(resp.DirectConnectGatewayAssociations) > 0 {
-			return fmt.Errorf("Direct Connect Gateway (%s) is not dissociated from VGW %s", rs.Primary.Attributes["dx_gateway_id"], rs.Primary.Attributes["vpn_gateway_id"])
+			return fmt.Errorf("Direct Connect Gateway (%s) is not dissociated from GW %s",
+				aws.StringValue(resp.DirectConnectGatewayAssociations[0].DirectConnectGatewayId),
+				aws.StringValue(resp.DirectConnectGatewayAssociations[0].AssociatedGateway.Id))
 		}
 	}
 	return nil
@@ -240,15 +442,42 @@ func testAccCheckAwsDxGatewayAssociationExists(name string) resource.TestCheckFu
 	}
 }
 
-func testAccDxGatewayAssociationConfig_basic(rName string, rBgpAsn int) string {
+func testAccDxGatewayAssociationConfigBase_vpnGatewaySingleAccount(rName string, rBgpAsn int) string {
 	return fmt.Sprintf(`
 resource "aws_dx_gateway" "test" {
-  name = %[1]q
+  name            = %[1]q
   amazon_side_asn = "%[2]d"
 }
 
 resource "aws_vpc" "test" {
   cidr_block = "10.255.255.0/28"
+
+  tags = {
+    Name = %[1]q
+  }
+}
+
+resource "aws_vpn_gateway" "test" {
+  tags = {
+    Name = %[1]q
+  }
+}
+
+resource "aws_vpn_gateway_attachment" "test" {
+  vpc_id         = "${aws_vpc.test.id}"
+  vpn_gateway_id = "${aws_vpn_gateway.test.id}"
+}
+`, rName, rBgpAsn)
+}
+
+func testAccDxGatewayAssociationConfigBase_vpnGatewayCrossAccount(rName string, rBgpAsn int) string {
+	return testAccAlternateAccountProviderConfig() + fmt.Sprintf(`
+# Creator
+data "aws_caller_identity" "creator" {}
+
+resource "aws_vpc" "test" {
+  cidr_block = "10.255.255.0/28"
+
   tags = {
     Name = %[1]q
   }
@@ -261,26 +490,135 @@ resource "aws_vpn_gateway" "test" {
 }
 
 resource "aws_vpn_gateway_attachment" "test" {
-  vpc_id = "${aws_vpc.test.id}"
+  vpc_id         = "${aws_vpc.test.id}"
   vpn_gateway_id = "${aws_vpn_gateway.test.id}"
 }
 
+# Accepter
+resource "aws_dx_gateway" "test" {
+  provider = "aws.alternate"
+
+  amazon_side_asn = %[2]d
+  name            = %[1]q
+}
+`, rName, rBgpAsn)
+}
+
+func testAccDxGatewayAssociationConfig_deprecatedSingleAccount(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationConfigBase_vpnGatewaySingleAccount(rName, rBgpAsn) + fmt.Sprintf(`
 resource "aws_dx_gateway_association" "test" {
-  dx_gateway_id = "${aws_dx_gateway.test.id}"
+  dx_gateway_id  = "${aws_dx_gateway.test.id}"
   vpn_gateway_id = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
 }
+`)
+}
+
+func testAccDxGatewayAssociationConfig_basicVpnGatewaySingleAccount(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationConfigBase_vpnGatewaySingleAccount(rName, rBgpAsn) + fmt.Sprintf(`
+resource "aws_dx_gateway_association" "test" {
+  dx_gateway_id         = "${aws_dx_gateway.test.id}"
+  associated_gateway_id = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
+}
+`)
+}
+
+func testAccDxGatewayAssociationConfig_basicVpnGatewayCrossAccount(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationConfigBase_vpnGatewayCrossAccount(rName, rBgpAsn) + fmt.Sprintf(`
+# Creator
+resource "aws_dx_gateway_association_proposal" "test" {
+  dx_gateway_id               = "${aws_dx_gateway.test.id}"
+  dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
+  associated_gateway_id       = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
+}
+
+# Accepter
+resource "aws_dx_gateway_association" "test" {
+  provider = "aws.alternate"
+
+  proposal_id                         = "${aws_dx_gateway_association_proposal.test.id}"
+  dx_gateway_id                       = "${aws_dx_gateway.test.id}"
+  associated_gateway_owner_account_id = "${data.aws_caller_identity.creator.account_id}"
+}
+`)
+}
+
+func testAccDxGatewayAssociationConfig_basicTransitGatewaySingleAccount(rName string, rBgpAsn int) string {
+	return fmt.Sprintf(`
+resource "aws_dx_gateway" "test" {
+  name            = %[1]q
+  amazon_side_asn = "%[2]d"
+}
+
+resource "aws_ec2_transit_gateway" "test" {
+  tags = {
+    Name = %[1]q
+  }
+}
+
+resource "aws_dx_gateway_association" "test" {
+  dx_gateway_id         = "${aws_dx_gateway.test.id}"
+  associated_gateway_id = "${aws_ec2_transit_gateway.test.id}"
+
+  allowed_prefixes = [
+    "10.255.255.0/30",
+    "10.255.255.8/30",
+  ]
+}
 `, rName, rBgpAsn)
 }
 
-func testAccDxGatewayAssociationConfig_multiVgws(rName1, rName2 string, rBgpAsn int) string {
+func testAccDxGatewayAssociationConfig_basicTransitGatewayCrossAccount(rName string, rBgpAsn int) string {
+	return testAccAlternateAccountProviderConfig() + fmt.Sprintf(`
+# Creator
+data "aws_caller_identity" "creator" {}
+
+# Accepter
+resource "aws_dx_gateway" "test" {
+  provider = "aws.alternate"
+
+  amazon_side_asn = %[2]d
+  name            = %[1]q
+}
+
+resource "aws_ec2_transit_gateway" "test" {
+  tags = {
+    Name = %[1]q
+  }
+}
+
+# Creator
+resource "aws_dx_gateway_association_proposal" "test" {
+  dx_gateway_id               = "${aws_dx_gateway.test.id}"
+  dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
+  associated_gateway_id       = "${aws_ec2_transit_gateway.test.id}"
+
+  allowed_prefixes = [
+    "10.255.255.0/30",
+    "10.255.255.8/30",
+  ]
+}
+
+# Accepter
+resource "aws_dx_gateway_association" "test" {
+  provider = "aws.alternate"
+
+  proposal_id                         = "${aws_dx_gateway_association_proposal.test.id}"
+  dx_gateway_id                       = "${aws_dx_gateway.test.id}"
+  associated_gateway_owner_account_id = "${data.aws_caller_identity.creator.account_id}"
+}
+`, rName, rBgpAsn)
+}
+
+func testAccDxGatewayAssociationConfig_multiVpnGatewaysSingleAccount(rName1, rName2 string, rBgpAsn int) string {
 	return fmt.Sprintf(`
 resource "aws_dx_gateway" "test" {
-  name = %[1]q
+  name            = %[1]q
   amazon_side_asn = "%[3]d"
 }
 
 resource "aws_vpc" "test1" {
   cidr_block = "10.255.255.16/28"
+
   tags = {
     Name = %[1]q
   }
@@ -293,17 +631,18 @@ resource "aws_vpn_gateway" "test1" {
 }
 
 resource "aws_vpn_gateway_attachment" "test1" {
-  vpc_id = "${aws_vpc.test1.id}"
+  vpc_id         = "${aws_vpc.test1.id}"
   vpn_gateway_id = "${aws_vpn_gateway.test1.id}"
 }
 
 resource "aws_dx_gateway_association" "test1" {
-  dx_gateway_id = "${aws_dx_gateway.test.id}"
-  vpn_gateway_id = "${aws_vpn_gateway_attachment.test1.vpn_gateway_id}"
+  dx_gateway_id         = "${aws_dx_gateway.test.id}"
+  associated_gateway_id = "${aws_vpn_gateway_attachment.test1.vpn_gateway_id}"
 }
 
 resource "aws_vpc" "test2" {
   cidr_block = "10.255.255.32/28"
+
   tags = {
     Name = %[2]q
   }
@@ -316,84 +655,94 @@ resource "aws_vpn_gateway" "test2" {
 }
 
 resource "aws_vpn_gateway_attachment" "test2" {
-  vpc_id = "${aws_vpc.test2.id}"
+  vpc_id         = "${aws_vpc.test2.id}"
   vpn_gateway_id = "${aws_vpn_gateway.test2.id}"
 }
 
 resource "aws_dx_gateway_association" "test2" {
-  dx_gateway_id = "${aws_dx_gateway.test.id}"
-  vpn_gateway_id = "${aws_vpn_gateway_attachment.test2.vpn_gateway_id}"
+  dx_gateway_id         = "${aws_dx_gateway.test.id}"
+  associated_gateway_id = "${aws_vpn_gateway_attachment.test2.vpn_gateway_id}"
 }
 `, rName1, rName2, rBgpAsn)
 }
 
-func testAccDxGatewayAssociationConfig_allowedPrefixes(rName string, rBgpAsn int) string {
-	return fmt.Sprintf(`
-resource "aws_dx_gateway" "test" {
-  name = %[1]q
-  amazon_side_asn = "%[2]d"
-}
+func testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewaySingleAccount(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationConfigBase_vpnGatewaySingleAccount(rName, rBgpAsn) + fmt.Sprintf(`
+resource "aws_dx_gateway_association" "test" {
+  dx_gateway_id         = "${aws_dx_gateway.test.id}"
+  associated_gateway_id = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
 
-resource "aws_vpc" "test" {
-  cidr_block = "10.255.255.0/28"
-  tags = {
-    Name = %[1]q
-  }
+  allowed_prefixes = [
+    "10.255.255.0/30",
+    "10.255.255.8/30",
+  ]
 }
-
-resource "aws_vpn_gateway" "test" {
-  tags = {
-    Name = %[1]q
-  }
+`)
 }
 
-resource "aws_vpn_gateway_attachment" "test" {
-  vpc_id = "${aws_vpc.test.id}"
-  vpn_gateway_id = "${aws_vpn_gateway.test.id}"
+func testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewaySingleAccountUpdated(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationConfigBase_vpnGatewaySingleAccount(rName, rBgpAsn) + fmt.Sprintf(`
+resource "aws_dx_gateway_association" "test" {
+  dx_gateway_id         = "${aws_dx_gateway.test.id}"
+  associated_gateway_id = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
+
+  allowed_prefixes = [
+    "10.255.255.8/29",
+  ]
+}
+`)
 }
 
-resource "aws_dx_gateway_association" "test" {
-  dx_gateway_id = "${aws_dx_gateway.test.id}"
-  vpn_gateway_id = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
+func testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewayCrossAccount(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationConfigBase_vpnGatewayCrossAccount(rName, rBgpAsn) + fmt.Sprintf(`
+# Creator
+resource "aws_dx_gateway_association_proposal" "test" {
+  dx_gateway_id               = "${aws_dx_gateway.test.id}"
+  dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
+  associated_gateway_id       = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
+
   allowed_prefixes = [
     "10.255.255.0/30",
     "10.255.255.8/30",
   ]
 }
-`, rName, rBgpAsn)
-}
 
-func testAccDxGatewayAssociationConfig_allowedPrefixesUpdated(rName string, rBgpAsn int) string {
-	return fmt.Sprintf(`
-resource "aws_dx_gateway" "test" {
-  name = %[1]q
-  amazon_side_asn = "%[2]d"
-}
+# Accepter
+resource "aws_dx_gateway_association" "test" {
+  provider = "aws.alternate"
 
-resource "aws_vpc" "test" {
-  cidr_block = "10.255.255.0/28"
-  tags = {
-    Name = %[1]q
-  }
-}
+  proposal_id                         = "${aws_dx_gateway_association_proposal.test.id}"
+  dx_gateway_id                       = "${aws_dx_gateway.test.id}"
+  associated_gateway_owner_account_id = "${data.aws_caller_identity.creator.account_id}"
 
-resource "aws_vpn_gateway" "test" {
-  tags = {
-    Name = %[1]q
-  }
+  allowed_prefixes = [
+    "10.255.255.8/29",
+  ]
+}
+`)
 }
 
-resource "aws_vpn_gateway_attachment" "test" {
-  vpc_id = "${aws_vpc.test.id}"
-  vpn_gateway_id = "${aws_vpn_gateway.test.id}"
+func testAccDxGatewayAssociationConfig_allowedPrefixesVpnGatewayCrossAccountUpdated(rName string, rBgpAsn int) string {
+	return testAccDxGatewayAssociationConfigBase_vpnGatewayCrossAccount(rName, rBgpAsn) + fmt.Sprintf(`
+# Creator
+resource "aws_dx_gateway_association_proposal" "test" {
+  dx_gateway_id               = "${aws_dx_gateway.test.id}"
+  dx_gateway_owner_account_id = "${aws_dx_gateway.test.owner_account_id}"
+  associated_gateway_id       = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
 }
 
+# Accepter
 resource "aws_dx_gateway_association" "test" {
-  dx_gateway_id = "${aws_dx_gateway.test.id}"
-  vpn_gateway_id = "${aws_vpn_gateway_attachment.test.vpn_gateway_id}"
+  provider = "aws.alternate"
+
+  proposal_id                         = "${aws_dx_gateway_association_proposal.test.id}"
+  dx_gateway_id                       = "${aws_dx_gateway.test.id}"
+  associated_gateway_owner_account_id = "${data.aws_caller_identity.creator.account_id}"
+
   allowed_prefixes = [
-    "10.255.255.8/29",
+    "10.255.255.0/30",
+    "10.255.255.8/30",
   ]
 }
-`, rName, rBgpAsn)
+`)
 }
diff --git a/aws/resource_aws_dx_gateway_test.go b/aws/resource_aws_dx_gateway_test.go
index 788b74327d2..bf78dd7568c 100644
--- a/aws/resource_aws_dx_gateway_test.go
+++ b/aws/resource_aws_dx_gateway_test.go
@@ -121,7 +121,7 @@ func TestAccAwsDxGateway_importComplex(t *testing.T) {
 		CheckDestroy: testAccCheckAwsDxGatewayDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccDxGatewayAssociationConfig_multiVgws(rName1, rName2, rBgpAsn),
+				Config: testAccDxGatewayAssociationConfig_multiVpnGatewaysSingleAccount(rName1, rName2, rBgpAsn),
 			},
 
 			{
diff --git a/examples/dx-gateway-cross-account-vgw-association/README.md b/examples/dx-gateway-cross-account-vgw-association/README.md
new file mode 100644
index 00000000000..25693883e58
--- /dev/null
+++ b/examples/dx-gateway-cross-account-vgw-association/README.md
@@ -0,0 +1,18 @@
+# Direct Connect Gateway Cross-Account VGW Association
+
+This example demonstrates how to create a VPN Gateway in one AWS account, create a Direct Connect Gateway in a second AWS account, and associate the VPN Gateway with the Direct Connect Gateway via the `aws_dx_gateway_association_proposal` and `aws_dx_gateway_association` resources.
+
+See [more in the Direct Connect Gateway documentation](https://docs.aws.amazon.com/directconnect/latest/UserGuide/direct-connect-gateways.html).
+
+## Running this example
+
+Either `cp terraform.template.tfvars terraform.tfvars` and modify that new file accordingly or provide variables via CLI:
+
+```
+terraform apply \
+	-var="aws_first_access_key=AAAAAAAAAAAAAAAAAAA" \
+	-var="aws_first_secret_key=SuperSecretKeyForAccount1" \
+	-var="aws_second_access_key=BBBBBBBBBBBBBBBBBBB" \
+	-var="aws_second_secret_key=SuperSecretKeyForAccount2" \
+	-var="aws_region=us-east-1"
+```
diff --git a/examples/dx-gateway-cross-account-vgw-association/main.tf b/examples/dx-gateway-cross-account-vgw-association/main.tf
new file mode 100644
index 00000000000..7aa0e306f28
--- /dev/null
+++ b/examples/dx-gateway-cross-account-vgw-association/main.tf
@@ -0,0 +1,64 @@
+// First account owns the VGW.
+provider "aws" {
+  alias = "first"
+
+  region     = "${var.aws_region}"
+  access_key = "${var.aws_first_access_key}"
+  secret_key = "${var.aws_first_secret_key}"
+}
+
+// Second account owns the DXGW.
+provider "aws" {
+  alias = "second"
+
+  region     = "${var.aws_region}"
+  access_key = "${var.aws_second_access_key}"
+  secret_key = "${var.aws_second_secret_key}"
+}
+
+data "aws_caller_identity" "first" {}
+
+resource "aws_vpc" "example" {
+  provider = "aws.first"
+
+  cidr_block = "10.255.255.0/28"
+
+  tags = {
+    Name = "terraform-example"
+  }
+}
+
+resource "aws_vpn_gateway" "example" {
+  provider = "aws.first"
+
+  vpc_id = "${aws_vpc.example.id}"
+
+  tags = {
+    Name = "terraform-example"
+  }
+}
+
+// Create the association proposal in the first account...
+resource "aws_dx_gateway_association_proposal" "example" {
+  provider = "aws.first"
+
+  dx_gateway_id               = "${aws_dx_gateway.example.id}"
+  dx_gateway_owner_account_id = "${aws_dx_gateway.example.owner_account_id}"
+  associated_gateway_id       = "${aws_vpn_gateway.example.id}"
+}
+
+// ...and accept it in the second account, creating the association.
+resource "aws_dx_gateway_association" "example" {
+  provider = "aws.second"
+
+  proposal_id                         = "${aws_dx_gateway_association_proposal.example.id}"
+  dx_gateway_id                       = "${aws_dx_gateway.example.id}"
+  associated_gateway_owner_account_id = "${data.aws_caller_identity.first.account_id}"
+}
+
+resource "aws_dx_gateway" "example" {
+  provider = "aws.second"
+
+  name            = "terraform-example"
+  amazon_side_asn = "64512"
+}
diff --git a/examples/dx-gateway-cross-account-vgw-association/terraform.template.tfvars b/examples/dx-gateway-cross-account-vgw-association/terraform.template.tfvars
new file mode 100644
index 00000000000..813b24302fe
--- /dev/null
+++ b/examples/dx-gateway-cross-account-vgw-association/terraform.template.tfvars
@@ -0,0 +1,9 @@
+# First account
+aws_first_access_key = "AAAAAAAAAAAAAAAAAAA"
+aws_first_secret_key = "SuperSecretKeyForAccount1"
+
+# Second account
+aws_second_access_key = "BBBBBBBBBBBBBBBBBBB"
+aws_second_secret_key = "SuperSecretKeyForAccount2"
+
+aws_region = "us-east-1"
diff --git a/examples/dx-gateway-cross-account-vgw-association/variables.tf b/examples/dx-gateway-cross-account-vgw-association/variables.tf
new file mode 100644
index 00000000000..ed1a71f53b1
--- /dev/null
+++ b/examples/dx-gateway-cross-account-vgw-association/variables.tf
@@ -0,0 +1,9 @@
+variable "aws_first_access_key" {}
+
+variable "aws_first_secret_key" {}
+
+variable "aws_second_access_key" {}
+
+variable "aws_second_secret_key" {}
+
+variable "aws_region" {}
diff --git a/website/docs/r/dx_gateway_association.html.markdown b/website/docs/r/dx_gateway_association.html.markdown
index 2cfe37ce2e9..4d84631f59a 100644
--- a/website/docs/r/dx_gateway_association.html.markdown
+++ b/website/docs/r/dx_gateway_association.html.markdown
@@ -3,16 +3,20 @@ layout: "aws"
 page_title: "AWS: aws_dx_gateway_association"
 sidebar_current: "docs-aws-resource-dx-gateway-association"
 description: |-
-  Associates a Direct Connect Gateway with a VGW.
+  Associates a Direct Connect Gateway with a VGW or transit gateway.
 ---
 
 # Resource: aws_dx_gateway_association
 
-Associates a Direct Connect Gateway with a VGW. For creating cross-account association proposals, see the [`aws_dx_gateway_association_proposal` resource](/docs/providers/aws/r/dx_gateway_association_proposal.html).
+Associates a Direct Connect Gateway with a VGW or transit gateway.
+
+To create a cross-account association, create an [`aws_dx_gateway_association_proposal` resource](/docs/providers/aws/r/dx_gateway_association_proposal.html)
+in the AWS account that owns the VGW or transit gateway and then accept the proposal in the AWS account that owns the Direct Connect Gateway
+by creating an `aws_dx_gateway_association` resource with the `proposal_id` and `associated_gateway_owner_account_id` attributes set.
 
 ## Example Usage
 
-### Basic
+### VPN Gateway Association
 
 ```hcl
 resource "aws_dx_gateway" "example" {
@@ -29,8 +33,29 @@ resource "aws_vpn_gateway" "example" {
 }
 
 resource "aws_dx_gateway_association" "example" {
-  dx_gateway_id  = "${aws_dx_gateway.example.id}"
-  vpn_gateway_id = "${aws_vpn_gateway.example.id}"
+  dx_gateway_id         = "${aws_dx_gateway.example.id}"
+  associated_gateway_id = "${aws_vpn_gateway.example.id}"
+}
+```
+
+### Transit Gateway Association
+
+```hcl
+resource "aws_dx_gateway" "example" {
+  name            = "example"
+  amazon_side_asn = "64512"
+}
+
+resource "aws_ec2_transit_gateway" "example" {}
+
+resource "aws_dx_gateway_association" "example" {
+  dx_gateway_id         = "${aws_dx_gateway.example.id}"
+  associated_gateway_id = "${aws_ec2_transit_gateway.example.id}"
+
+  allowed_prefixes = [
+    "10.255.255.0/30",
+    "10.255.255.8/30",
+  ]
 }
 ```
 
@@ -51,8 +76,8 @@ resource "aws_vpn_gateway" "example" {
 }
 
 resource "aws_dx_gateway_association" "example" {
-  dx_gateway_id  = "${aws_dx_gateway.example.id}"
-  vpn_gateway_id = "${aws_vpn_gateway.example.id}"
+  dx_gateway_id         = "${aws_dx_gateway.example.id}"
+  associated_gateway_id = "${aws_vpn_gateway.example.id}"
 
   allowed_prefixes = [
     "210.52.109.0/24",
@@ -61,12 +86,23 @@ resource "aws_dx_gateway_association" "example" {
 }
 ```
 
+A full example of how to create a VPN Gateway in one AWS account, create a Direct Connect Gateway in a second AWS account, and associate the VPN Gateway with the Direct Connect Gateway via the `aws_dx_gateway_association_proposal` and `aws_dx_gateway_association` resources can be found in [the `./examples/dx-gateway-cross-account-vgw-association` directory within the Github Repository](https://github.com/terraform-providers/terraform-provider-aws/tree/master/examples/dx-gateway-cross-account-vgw-association).
+
 ## Argument Reference
 
+~> **NOTE:** `dx_gateway_id` plus one of `associated_gateway_id`, or `vpn_gateway_id` must be specified for single account Direct Connect gateway associations.
+
 The following arguments are supported:
 
 * `dx_gateway_id` - (Required) The ID of the Direct Connect gateway.
-* `vpn_gateway_id` - (Required) The ID of the VGW with which to associate the gateway.
+* `associated_gateway_id` - (Optional) The ID of the VGW or transit gateway with which to associate the Direct Connect gateway.
+Used for single account Direct Connect gateway associations.
+* `vpn_gateway_id` - (Optional) *Deprecated:* Use `associated_gateway_id` instead. The ID of the VGW with which to associate the gateway.
+Used for single account Direct Connect gateway associations.
+* `associated_gateway_owner_account_id` - (Optional) The ID of the AWS account that owns the VGW or transit gateway with which to associate the Direct Connect gateway.
+Used for cross-account Direct Connect gateway associations.
+* `proposal_id` - (Optional) The ID of the Direct Connect gateway association proposal.
+Used for cross-account Direct Connect gateway associations.
 * `allowed_prefixes` - (Optional) VPC prefixes (CIDRs) to advertise to the Direct Connect gateway. Defaults to the CIDR block of the VPC associated with the Virtual Gateway. To enable drift detection, must be configured.
 
 ## Attributes Reference
@@ -74,7 +110,9 @@ The following arguments are supported:
 In addition to all arguments above, the following attributes are exported:
 
 * `id` - The ID of the Direct Connect gateway association resource.
+* `associated_gateway_type` - The type of the associated gateway, `transitGateway` or `virtualPrivateGateway`.
 * `dx_gateway_association_id` - The ID of the Direct Connect gateway association.
+* `dx_gateway_owner_account_id` - The ID of the AWS account that owns the Direct Connect gateway.
 
 ## Timeouts
 
@@ -87,7 +125,7 @@ In addition to all arguments above, the following attributes are exported:
 
 ## Import
 
-Direct Connect gateway associations can be imported using `dx_gateway_id` together with `vpn_gateway_id`,
+Direct Connect gateway associations can be imported using `dx_gateway_id` together with `associated_gateway_id`,
 e.g.
 
 ```
diff --git a/website/docs/r/dx_gateway_association_proposal.html.markdown b/website/docs/r/dx_gateway_association_proposal.html.markdown
index 8ee72a14a2d..725d25d9205 100644
--- a/website/docs/r/dx_gateway_association_proposal.html.markdown
+++ b/website/docs/r/dx_gateway_association_proposal.html.markdown
@@ -13,40 +13,34 @@ Manages a Direct Connect Gateway Association Proposal, typically for enabling cr
 ## Example Usage
 
 ```hcl
-resource "aws_dx_gateway" "example" {
-  name            = "example"
-  amazon_side_asn = "64512"
-}
-
-resource "aws_vpc" "example" {
-  cidr_block = "10.255.255.0/28"
-}
-
-resource "aws_vpn_gateway" "example" {
-  vpc_id = "${aws_vpc.example.id}"
-}
-
 resource "aws_dx_gateway_association_proposal" "example" {
   dx_gateway_id               = "${aws_dx_gateway.example.id}"
   dx_gateway_owner_account_id = "${aws_dx_gateway.example.owner_account_id}"
-  vpn_gateway_id              = "${aws_vpn_gateway.example.id}"
+  associated_gateway_id       = "${aws_vpn_gateway.example.id}"
 }
 ```
 
+A full example of how to create a VPN Gateway in one AWS account, create a Direct Connect Gateway in a second AWS account, and associate the VPN Gateway with the Direct Connect Gateway via the `aws_dx_gateway_association_proposal` and `aws_dx_gateway_association` resources can be found in [the `./examples/dx-gateway-cross-account-vgw-association` directory within the Github Repository](https://github.com/terraform-providers/terraform-provider-aws/tree/master/examples/dx-gateway-cross-account-vgw-association).
+
 ## Argument Reference
 
+~> **NOTE:** One of `associated_gateway_id`, or `vpn_gateway_id` must be specified.
+
 The following arguments are supported:
 
 * `dx_gateway_id` - (Required) Direct Connect Gateway identifier.
-* `dx_gateway_owner_account_id` - (Required) AWS Account identifier of the Direct Connect Gateway.
-* `vpn_gateway_id` - (Required) Virtual Gateway identifier to associate with the Direct Connect Gateway.
+* `dx_gateway_owner_account_id` - (Required) AWS Account identifier of the Direct Connect Gateway's owner.
+* `associated_gateway_id` - (Optional) The ID of the VGW or transit gateway with which to associate the Direct Connect gateway.
+* `vpn_gateway_id` - (Optional) *Deprecated:* Use `associated_gateway_id` instead. Virtual Gateway identifier to associate with the Direct Connect Gateway.
 * `allowed_prefixes` - (Optional) VPC prefixes (CIDRs) to advertise to the Direct Connect gateway. Defaults to the CIDR block of the VPC associated with the Virtual Gateway. To enable drift detection, must be configured.
 
 ## Attributes Reference
 
 In addition to all arguments above, the following attributes are exported:
 
-* `id` - Direct Connect Gateway Association Proposal identifier
+* `id` - Direct Connect Gateway Association Proposal identifier.
+* `associated_gateway_owner_account_id` - The ID of the AWS account that owns the VGW or transit gateway with which to associate the Direct Connect gateway.
+* `associated_gateway_type` - The type of the associated gateway, `transitGateway` or `virtualPrivateGateway`.
 
 ## Import