diff --git a/src/execution/index.ts b/src/execution/index.ts
index ff339deb88..f3e63b7858 100644
--- a/src/execution/index.ts
+++ b/src/execution/index.ts
@@ -13,6 +13,11 @@ export {
   subscribe,
 } from './execute.js';
 
+export {
+  legacyExecuteIncrementally,
+  legacyExecuteQueryOrMutationOrSubscriptionEvent,
+} from './legacyExecuteIncrementally.js';
+
 export type { ExecutionArgs } from './execute.js';
 
 export type { ValidatedExecutionArgs } from './Executor.js';
diff --git a/src/execution/legacyExecuteIncrementally.ts b/src/execution/legacyExecuteIncrementally.ts
new file mode 100644
index 0000000000..a3b0856bad
--- /dev/null
+++ b/src/execution/legacyExecuteIncrementally.ts
@@ -0,0 +1,299 @@
+import { AccumulatorMap } from '../jsutils/AccumulatorMap.js';
+import { getBySet } from '../jsutils/getBySet.js';
+import { invariant } from '../jsutils/invariant.js';
+import { isSameSet } from '../jsutils/isSameSet.js';
+import type { ObjMap } from '../jsutils/ObjMap.js';
+import { addPath, pathToArray } from '../jsutils/Path.js';
+import type { PromiseOrValue } from '../jsutils/PromiseOrValue.js';
+
+import type { GraphQLError } from '../error/GraphQLError.js';
+
+import type { DeferUsageSet, ExecutionPlan } from './buildExecutionPlan.js';
+import type {
+  DeferUsage,
+  FieldDetails,
+  GroupedFieldSet,
+} from './collectFields.js';
+import type { ExecutionArgs } from './execute.js';
+import { validateExecutionArgs } from './execute.js';
+import type { ValidatedExecutionArgs } from './Executor.js';
+import { Executor } from './Executor.js';
+import type { ExperimentalIncrementalExecutionResults } from './IncrementalPublisher.js';
+import type {
+  PayloadPublisher,
+  SubsequentPayloadPublisher,
+} from './PayloadPublisher.js';
+import type {
+  DeferredFragmentRecord,
+  DeliveryGroup,
+  ExecutionResult,
+  FailedExecutionGroup,
+  StreamItemsRecordResult,
+  StreamRecord,
+  SuccessfulExecutionGroup,
+} from './types.js';
+import { isDeferredFragmentRecord } from './types.js';
+
+interface InitialIncrementalExecutionResult<
+  TData = ObjMap<unknown>,
+  TExtensions = ObjMap<unknown>,
+> extends ExecutionResult<TData, TExtensions> {
+  data: TData;
+  hasNext: true;
+  extensions?: TExtensions;
+}
+
+interface SubsequentIncrementalExecutionResult<
+  TData = unknown,
+  TExtensions = ObjMap<unknown>,
+> {
+  incremental?: ReadonlyArray<IncrementalResult<TData, TExtensions>>;
+  hasNext: boolean;
+  extensions?: TExtensions;
+}
+
+type IncrementalResult<TData = unknown, TExtensions = ObjMap<unknown>> =
+  | IncrementalDeferResult<TData, TExtensions>
+  | IncrementalStreamResult<TData, TExtensions>;
+
+interface IncrementalDeferResult<
+  TData = ObjMap<unknown>,
+  TExtensions = ObjMap<unknown>,
+> extends ExecutionResult<TData, TExtensions> {
+  path: ReadonlyArray<string | number>;
+  label?: string;
+}
+
+interface IncrementalStreamResult<
+  TData = ReadonlyArray<unknown>,
+  TExtensions = ObjMap<unknown>,
+> {
+  errors?: ReadonlyArray<GraphQLError>;
+  items: TData | null;
+  path: ReadonlyArray<string | number>;
+  label?: string;
+  extensions?: TExtensions;
+}
+
+export function legacyExecuteIncrementally(
+  args: ExecutionArgs,
+): PromiseOrValue<
+  | ExecutionResult
+  | ExperimentalIncrementalExecutionResults<
+      InitialIncrementalExecutionResult,
+      SubsequentIncrementalExecutionResult
+    >
+> {
+  // If a valid execution context cannot be created due to incorrect arguments,
+  // a "Response" with only errors is returned.
+  const validatedExecutionArgs = validateExecutionArgs(args);
+
+  // Return early errors if execution context failed.
+  if (!('schema' in validatedExecutionArgs)) {
+    return { errors: validatedExecutionArgs };
+  }
+
+  return legacyExecuteQueryOrMutationOrSubscriptionEvent(
+    validatedExecutionArgs,
+  );
+}
+
+export function legacyExecuteQueryOrMutationOrSubscriptionEvent(
+  validatedExecutionArgs: ValidatedExecutionArgs,
+): PromiseOrValue<
+  | ExecutionResult
+  | ExperimentalIncrementalExecutionResults<
+      InitialIncrementalExecutionResult,
+      SubsequentIncrementalExecutionResult
+    >
+> {
+  const executor = new Executor(
+    validatedExecutionArgs,
+    buildBranchingExecutionPlan,
+    getBranchingPayloadPublisher,
+  );
+  return executor.executeQueryOrMutationOrSubscriptionEvent();
+}
+
+function buildBranchingExecutionPlan(
+  originalGroupedFieldSet: GroupedFieldSet,
+  parentDeferUsages: DeferUsageSet = new Set<DeferUsage>(),
+): ExecutionPlan {
+  const groupedFieldSet = new AccumulatorMap<string, FieldDetails>();
+
+  const newGroupedFieldSets = new Map<
+    DeferUsageSet,
+    AccumulatorMap<string, FieldDetails>
+  >();
+
+  for (const [responseKey, fieldGroup] of originalGroupedFieldSet) {
+    for (const fieldDetails of fieldGroup) {
+      const deferUsage = fieldDetails.deferUsage;
+      const deferUsageSet =
+        deferUsage === undefined
+          ? new Set<DeferUsage>()
+          : new Set([deferUsage]);
+      if (isSameSet(parentDeferUsages, deferUsageSet)) {
+        groupedFieldSet.add(responseKey, fieldDetails);
+      } else {
+        let newGroupedFieldSet = getBySet(newGroupedFieldSets, deferUsageSet);
+        if (newGroupedFieldSet === undefined) {
+          newGroupedFieldSet = new AccumulatorMap();
+          newGroupedFieldSets.set(deferUsageSet, newGroupedFieldSet);
+        }
+        newGroupedFieldSet.add(responseKey, fieldDetails);
+      }
+    }
+  }
+
+  return {
+    groupedFieldSet,
+    newGroupedFieldSets,
+  };
+}
+
+function getBranchingPayloadPublisher(): PayloadPublisher<
+  InitialIncrementalExecutionResult,
+  SubsequentIncrementalExecutionResult
+> {
+  const indices = new Map<StreamRecord, number>();
+
+  return {
+    getInitialPayload,
+    getSubsequentPayloadPublisher,
+  };
+
+  function getInitialPayload(
+    data: ObjMap<unknown>,
+    errors: ReadonlyArray<GraphQLError> | undefined,
+    newRootNodes: ReadonlyArray<DeliveryGroup>,
+  ): InitialIncrementalExecutionResult {
+    for (const node of newRootNodes) {
+      if (!isDeferredFragmentRecord(node)) {
+        indices.set(node, 0);
+      }
+    }
+
+    return errors === undefined
+      ? { data, hasNext: true }
+      : { errors, data, hasNext: true };
+  }
+
+  function getSubsequentPayloadPublisher(): SubsequentPayloadPublisher<SubsequentIncrementalExecutionResult> {
+    const incremental: Array<IncrementalResult> = [];
+
+    return {
+      addFailedDeferredFragmentRecord,
+      addSuccessfulDeferredFragmentRecord,
+      addFailedStreamRecord,
+      addSuccessfulStreamRecord,
+      addStreamItems,
+      getSubsequentPayload,
+    };
+
+    function addFailedDeferredFragmentRecord(
+      deferredFragmentRecord: DeferredFragmentRecord,
+      failedExecutionGroup: FailedExecutionGroup,
+    ): void {
+      const { path, label } = deferredFragmentRecord;
+      const incrementalEntry: IncrementalDeferResult = {
+        errors: failedExecutionGroup.errors,
+        data: null,
+        path: pathToArray(path),
+      };
+      incrementalEntry.path = pathToArray(path);
+      if (label !== undefined) {
+        incrementalEntry.label = label;
+      }
+      incremental.push(incrementalEntry);
+    }
+
+    function addSuccessfulDeferredFragmentRecord(
+      deferredFragmentRecord: DeferredFragmentRecord,
+      newRootNodes: ReadonlyArray<DeliveryGroup>,
+      successfulExecutionGroups: ReadonlyArray<SuccessfulExecutionGroup>,
+    ): void {
+      for (const node of newRootNodes) {
+        if (!isDeferredFragmentRecord(node)) {
+          indices.set(node, 0);
+        }
+      }
+
+      for (const successfulExecutionGroup of successfulExecutionGroups) {
+        const { path, label } = deferredFragmentRecord;
+        const incrementalEntry: IncrementalDeferResult = {
+          ...successfulExecutionGroup.result,
+          path: pathToArray(path),
+        };
+        if (label !== undefined) {
+          incrementalEntry.label = label;
+        }
+        incremental.push(incrementalEntry);
+      }
+    }
+
+    function addFailedStreamRecord(
+      streamRecord: StreamRecord,
+      errors: ReadonlyArray<GraphQLError>,
+    ): void {
+      const { path, label } = streamRecord;
+      const index = indices.get(streamRecord);
+      invariant(index !== undefined);
+      const incrementalEntry: IncrementalStreamResult = {
+        errors,
+        items: null,
+        path: pathToArray(addPath(path, index, undefined)),
+      };
+      if (label !== undefined) {
+        incrementalEntry.label = label;
+      }
+      incremental.push(incrementalEntry);
+      indices.delete(streamRecord);
+    }
+
+    function addSuccessfulStreamRecord(streamRecord: StreamRecord): void {
+      indices.delete(streamRecord);
+    }
+
+    function addStreamItems(
+      streamRecord: StreamRecord,
+      newRootNodes: ReadonlyArray<DeliveryGroup> | undefined,
+      result: StreamItemsRecordResult,
+    ): void {
+      if (newRootNodes !== undefined) {
+        for (const node of newRootNodes) {
+          if (!isDeferredFragmentRecord(node)) {
+            indices.set(node, 0);
+          }
+        }
+      }
+
+      const { path, label } = streamRecord;
+      const index = indices.get(streamRecord);
+      invariant(index !== undefined);
+      const incrementalEntry: IncrementalStreamResult = {
+        ...result,
+        path: pathToArray(addPath(path, index, undefined)),
+      };
+      if (label !== undefined) {
+        incrementalEntry.label = label;
+      }
+      incremental.push(incrementalEntry);
+    }
+
+    function getSubsequentPayload(
+      hasNext: boolean,
+    ): SubsequentIncrementalExecutionResult | undefined {
+      if (incremental.length > 0) {
+        const subsequentIncrementalExecutionResult: SubsequentIncrementalExecutionResult =
+          { hasNext };
+
+        if (incremental.length > 0) {
+          subsequentIncrementalExecutionResult.incremental = incremental;
+        }
+
+        return subsequentIncrementalExecutionResult;
+      }
+    }
+  }
+}