diff --git a/src/main/proto/ga4gh/read_service.proto b/src/main/proto/ga4gh/read_service.proto
index 99280089..70741586 100644
--- a/src/main/proto/ga4gh/read_service.proto
+++ b/src/main/proto/ga4gh/read_service.proto
@@ -9,12 +9,24 @@ service ReadService {
   //
   // `POST /readgroupsets/search` must accept a JSON version of
   // `SearchReadGroupSetsRequest` as the post body and will return a JSON
-  // version of `SearchReadGroupSetsResponse`. Only readgroups that
-  // match an optionally supplied bioSampleId will be included in the
-  // response.
+  // version of `SearchReadGroupSetsResponse`.
   rpc SearchReadGroupSets(SearchReadGroupSetsRequest)
       returns (SearchReadGroupSetsResponse);
 
+  // Gets a list of `ReadGroup` matching the search criteria.
+  //
+  // `POST /readgroups/search` must accept a JSON version of
+  // `SearchReadGroupsRequest` as the post body and will return a JSON
+  // version of `SearchReadGroupsResponse`.
+  rpc SearchReadGroups(SearchReadGroupsRequest)
+      returns (SearchReadGroupsResponse);
+  
+  // Gets a `ReadGroup` by ID.
+  //
+  // `GET /readgroups/{read_group_id}` will return a JSON version of
+  // `ReadGroup`.
+  rpc GetReadGroup(GetReadGroupRequest) returns (ReadGroup);
+
   // Gets a `ReadGroupSet` by ID.
   //
   // `GET /readgroupsets/{read_group_set_id}` will return a JSON version of
@@ -60,10 +72,6 @@ message SearchReadGroupSetsRequest {
   // Only return read group sets with this name (case-sensitive, exact match).
   string name = 2;
 
-  //  Specifying the id of a BioSample record will return only readgroups
-  //  with the given bioSampleId.
-  string bio_sample_id = 3;
-
   // Specifies the maximum number of results to return in a single page.
   // If unspecified, a system default will be used.
   int32 page_size = 4;
@@ -91,6 +99,52 @@ message GetReadGroupSetRequest {
   string read_group_set_id = 1;
 }
 
+// ******************  /readgroups  *********************/
+
+// This request maps to the body of `POST /readgroups/search` as JSON.
+
+
+message SearchReadGroupsRequest {
+  // The dataset to search (required).
+  string dataset_id = 1;
+  
+  // The read_group_set to search (optional).
+  string read_group_set_id = 2;
+
+  // Only return read groups with this name (case-sensitive, exact match).
+  string name = 3;
+
+  //  Specifying the id of a BioSample record will return only readgroups
+  //  with the given bioSampleId.
+  string bio_sample_id = 4;
+
+  // Specifies the maximum number of results to return in a single page.
+  // If unspecified, a system default will be used.
+  int32 page_size = 5;
+
+  // The continuation token, which is used to page through large result sets.
+  // To get the next page of results, set this parameter to the value of
+  // `next_page_token` from the previous response.
+  string page_token = 6;
+}
+
+// This is the response from `POST /readgroups/search` expressed as JSON.
+message SearchReadGroupsResponse {
+  // The list of matching read groups.
+  repeated ReadGroupSet read_groups = 1;
+
+  // The continuation token, which is used to page through large result sets.
+  // Provide this value in a subsequent request to return the next page of
+  // results. This field will be empty if there aren't any additional results.
+  string next_page_token = 2;
+}
+
+// This request maps to the URL `GET /readgroups/{read_group_id}`.
+message GetReadGroupRequest {
+  // The ID of the `ReadGroup` to be retrieved.
+  string read_group_id = 1;
+}
+
 // ******************  /reads  *********************
 // This request maps to the body of `POST /reads/search` as JSON.
 //
diff --git a/src/main/proto/ga4gh/reads.proto b/src/main/proto/ga4gh/reads.proto
index 04f5714d..5ae812ef 100644
--- a/src/main/proto/ga4gh/reads.proto
+++ b/src/main/proto/ga4gh/reads.proto
@@ -32,6 +32,9 @@ message ReadGroup {
 
   // The ID of the dataset this read group belongs to.
   string dataset_id = 2;
+  
+  // The ID of the read group set this read group belongs to.
+  string read_group_set_id = 15;
 
   // The read group name.
   string name = 3;
@@ -64,6 +67,7 @@ message ReadGroup {
   // Statistical data on reads in this read group.
   ReadStats stats = 11;
 
+  // Program can be used to track the provenance of how read data was generated.
   repeated Program programs = 12;
 
   // The ID of the reference set to which the reads in this read group are
@@ -76,6 +80,8 @@ message ReadGroup {
 
 // A ReadGroupSet is a logical collection of ReadGroups. Typically one
 // ReadGroupSet represents all the reads from one experimental sample.
+// All read groups require that all readgroups in the set are mapped to
+// the same referenceSet.
 message ReadGroupSet {
   // The read group set ID.
   string id = 1;
@@ -88,12 +94,9 @@ message ReadGroupSet {
 
   // Statistical data on reads in this read group set.
   ReadStats stats = 4;
-
-  // The read groups in this set.
-  repeated ReadGroup read_groups = 5;
-
-  // NB: we require that all readgroups in the set are mapped to the same
-  // referenceSet.
+  
+  // IDs of the Read Groups in this ReadGroupSet
+  repeated string read_group_ids = 6;
 }
 
 // A linear alignment describes the alignment of a read to a Reference, using a
@@ -110,8 +113,7 @@ message LinearAlignment {
   int32 mapping_quality = 2;
 
   // Represents the local alignment of this sequence (alignment matches, indels,
-  // etc)
-  // versus the reference.
+  // etc) versus the reference.
   repeated CigarUnit cigar = 3;
 }