diff --git a/packages/data/src/redux-store/index.js b/packages/data/src/redux-store/index.js
index 1ff1faed5695b2..cdbc5ec59468a9 100644
--- a/packages/data/src/redux-store/index.js
+++ b/packages/data/src/redux-store/index.js
@@ -111,6 +111,16 @@ function createResolversCache() {
 export default function createReduxStore( key, options ) {
 	const privateActions = {};
 	const privateSelectors = {};
+	const privateRegistrationFunctions = {
+		privateActions,
+		registerPrivateActions: ( actions ) => {
+			Object.assign( privateActions, actions );
+		},
+		privateSelectors,
+		registerPrivateSelectors: ( selectors ) => {
+			Object.assign( privateSelectors, selectors );
+		},
+	};
 	const storeDescriptor = {
 		name: key,
 		instantiate: ( registry ) => {
@@ -141,6 +151,9 @@ export default function createReduxStore( key, options ) {
 				registry,
 				thunkArgs
 			);
+			// Expose the private registration functions on the store
+			// so they can be copied to a sub registry in registry.js.
+			lock( store, privateRegistrationFunctions );
 			const resolversCache = createResolversCache();
 
 			let resolvers;
@@ -260,14 +273,10 @@ export default function createReduxStore( key, options ) {
 		},
 	};
 
-	lock( storeDescriptor, {
-		registerPrivateActions: ( actions ) => {
-			Object.assign( privateActions, actions );
-		},
-		registerPrivateSelectors: ( selectors ) => {
-			Object.assign( privateSelectors, selectors );
-		},
-	} );
+	// Expose the private registration functions on the store
+	// descriptor. That's a natural choice since that's where the
+	// public actions and selectors are stored .
+	lock( storeDescriptor, privateRegistrationFunctions );
 
 	return storeDescriptor;
 }
diff --git a/packages/data/src/registry.js b/packages/data/src/registry.js
index df46227257f363..7a5668505b7127 100644
--- a/packages/data/src/registry.js
+++ b/packages/data/src/registry.js
@@ -14,6 +14,7 @@ import deprecated from '@wordpress/deprecated';
 import createReduxStore from './redux-store';
 import coreDataStore from './store';
 import { createEmitter } from './utils/emitter';
+import { lock, unlock } from './experiments';
 
 /** @typedef {import('./types').StoreDescriptor} StoreDescriptor */
 
@@ -245,6 +246,22 @@ export function createRegistry( storeConfigs = {}, parent = null ) {
 		};
 		stores[ name ] = store;
 		store.subscribe( globalListener );
+
+		// Copy private actions and selectors from the parent store.
+		if ( parent ) {
+			try {
+				unlock( store.store ).registerPrivateActions(
+					unlock( parent ).privateActionsOf( name )
+				);
+				unlock( store.store ).registerPrivateSelectors(
+					unlock( parent ).privateSelectorsOf( name )
+				);
+			} catch ( e ) {
+				// unlock() throws if store.store was not locked.
+				// The error indicates there's nothing to do here so let's
+				// ignore it.
+			}
+		}
 	}
 
 	/**
@@ -334,5 +351,24 @@ export function createRegistry( storeConfigs = {}, parent = null ) {
 		parent.subscribe( globalListener );
 	}
 
-	return withPlugins( registry );
+	const registryWithPlugins = withPlugins( registry );
+	lock( registryWithPlugins, {
+		privateActionsOf: ( name ) => {
+			try {
+				return unlock( stores[ name ].store ).privateActions;
+			} catch ( e ) {
+				// unlock() throws an error the store was not locked – this means
+				// there no private actions are available
+				return {};
+			}
+		},
+		privateSelectorsOf: ( name ) => {
+			try {
+				return unlock( stores[ name ].store ).privateSelectors;
+			} catch ( e ) {
+				return {};
+			}
+		},
+	} );
+	return registryWithPlugins;
 }
diff --git a/packages/data/src/test/privateAPIs.js b/packages/data/src/test/privateAPIs.js
index 00b9e8d866c213..ea6eb53eda3c87 100644
--- a/packages/data/src/test/privateAPIs.js
+++ b/packages/data/src/test/privateAPIs.js
@@ -38,32 +38,34 @@ describe( 'Private data APIs', () => {
 	function setPublicPrice( price ) {
 		return { type: 'SET_PUBLIC_PRICE', price };
 	}
-	function createStore() {
-		const groceryStore = createReduxStore( 'grocer', {
-			selectors: {
-				getPublicPrice,
-				getState: ( state ) => state,
-			},
-			actions: { setPublicPrice },
-			reducer: ( state, action ) => {
-				if ( action?.type === 'SET_PRIVATE_PRICE' ) {
-					return {
-						...state,
-						secretDiscount: action?.price,
-					};
-				} else if ( action?.type === 'SET_PUBLIC_PRICE' ) {
-					return {
-						...state,
-						price: action?.price,
-					};
-				}
+	const storeName = 'grocer';
+	const storeDescriptor = {
+		selectors: {
+			getPublicPrice,
+			getState: ( state ) => state,
+		},
+		actions: { setPublicPrice },
+		reducer: ( state, action ) => {
+			if ( action?.type === 'SET_PRIVATE_PRICE' ) {
 				return {
-					price: 1000,
-					secretDiscount: 800,
-					...( state || {} ),
+					...state,
+					secretDiscount: action?.price,
 				};
-			},
-		} );
+			} else if ( action?.type === 'SET_PUBLIC_PRICE' ) {
+				return {
+					...state,
+					price: action?.price,
+				};
+			}
+			return {
+				price: 1000,
+				secretDiscount: 800,
+				...( state || {} ),
+			};
+		},
+	};
+	function createStore() {
+		const groceryStore = createReduxStore( storeName, storeDescriptor );
 		registry.register( groceryStore );
 		return groceryStore;
 	}
@@ -126,6 +128,28 @@ describe( 'Private data APIs', () => {
 			const unlockedSelectors = unlock( registry.select( groceryStore ) );
 			expect( unlockedSelectors.getPublicPrice() ).toEqual( 1000 );
 		} );
+
+		it( 'should support sub registries', () => {
+			const groceryStore = registry.registerStore(
+				storeName,
+				storeDescriptor
+			);
+			unlock( groceryStore ).registerPrivateSelectors( {
+				getSecretDiscount,
+			} );
+			const subRegistry = createRegistry( {}, registry );
+			subRegistry.registerStore( storeName, storeDescriptor );
+
+			const parentPrivateSelectors = unlock(
+				registry.select( storeName )
+			);
+			expect( parentPrivateSelectors.getSecretDiscount() ).toEqual( 800 );
+
+			const subPrivateSelectors = unlock(
+				subRegistry.select( storeName )
+			);
+			expect( subPrivateSelectors.getSecretDiscount() ).toEqual( 800 );
+		} );
 	} );
 
 	describe( 'private actions', () => {
@@ -224,5 +248,37 @@ describe( 'Private data APIs', () => {
 				unlock( registry.select( groceryStore ) ).getSecretDiscount()
 			).toEqual( 100 );
 		} );
+
+		it( 'should support sub registries', () => {
+			const groceryStore = createStore();
+			unlock( groceryStore ).registerPrivateSelectors( {
+				getSecretDiscount,
+			} );
+			unlock( groceryStore ).registerPrivateActions( {
+				setSecretDiscount,
+			} );
+			const subRegistry = createRegistry( {}, registry );
+			subRegistry.registerStore( storeName, storeDescriptor );
+
+			const parentPrivateActions = unlock(
+				registry.dispatch( storeName )
+			);
+			const parentPrivateSelectors = unlock(
+				registry.select( storeName )
+			);
+
+			const subPrivateActions = unlock(
+				subRegistry.dispatch( storeName )
+			);
+			const subPrivateSelectors = unlock(
+				subRegistry.select( storeName )
+			);
+
+			parentPrivateActions.setSecretDiscount( 400 );
+			subPrivateActions.setSecretDiscount( 478 );
+
+			expect( parentPrivateSelectors.getSecretDiscount() ).toEqual( 400 );
+			expect( subPrivateSelectors.getSecretDiscount() ).toEqual( 478 );
+		} );
 	} );
 } );