diff --git a/editor/src/components/editor/store/dispatch-strategies.tsx b/editor/src/components/editor/store/dispatch-strategies.tsx
index 67f2d990e5ca..ea4ed8b30e40 100644
--- a/editor/src/components/editor/store/dispatch-strategies.tsx
+++ b/editor/src/components/editor/store/dispatch-strategies.tsx
@@ -654,12 +654,24 @@ export function handleStrategies(
   if (MeasureDispatchTime) {
     window.performance.mark('strategies_begin')
   }
-  const { unpatchedEditorState, patchedEditorState, newStrategyState } = handleStrategiesInner(
-    strategies,
-    dispatchedActions,
-    storedState,
-    result,
-  )
+  let unpatchedEditorState: EditorState
+  let patchedEditorState: EditorState
+  let newStrategyState: StrategyState
+  if (storedState.projectServerState.isMyProject === 'no') {
+    unpatchedEditorState = result.unpatchedEditor
+    patchedEditorState = result.unpatchedEditor
+    newStrategyState = result.strategyState
+  } else {
+    const strategiesResult = handleStrategiesInner(
+      strategies,
+      dispatchedActions,
+      storedState,
+      result,
+    )
+    unpatchedEditorState = strategiesResult.unpatchedEditorState
+    patchedEditorState = strategiesResult.patchedEditorState
+    newStrategyState = strategiesResult.newStrategyState
+  }
 
   const patchedEditorWithMetadata: EditorState = {
     ...patchedEditorState,
diff --git a/editor/src/components/editor/store/dispatch.tsx b/editor/src/components/editor/store/dispatch.tsx
index aa4e66a7a269..e7a3ac5fd93d 100644
--- a/editor/src/components/editor/store/dispatch.tsx
+++ b/editor/src/components/editor/store/dispatch.tsx
@@ -105,168 +105,195 @@ function processAction(
   action: EditorAction,
   spyCollector: UiJsxCanvasContextData,
 ): EditorStoreUnpatched {
+  let shouldProcessAction: boolean = true
+  // By default when the current user does not own the project and the action is non-transient prevent actions from running...
+  if (editorStoreUnpatched.projectServerState.isMyProject === 'no' && !isTransientAction(action)) {
+    // ...Unless they're more critical to the running of the editor in this case.
+    const allowedNonOwnerAction =
+      action.action === 'UPDATE_FROM_WORKER' ||
+      action.action === 'UPDATE_TOP_LEVEL_ELEMENTS_FROM_COLLABORATION_UPDATE'
+    shouldProcessAction = allowedNonOwnerAction
+  }
+  // When the current user does own the project...
+  if (editorStoreUnpatched.projectServerState.isMyProject === 'yes') {
+    // ...Disallow these updates as they're coming from non-owners.
+    shouldProcessAction = action.action !== 'UPDATE_TOP_LEVEL_ELEMENTS_FROM_COLLABORATION_UPDATE'
+  }
+
   let working = editorStoreUnpatched
-  // Sidestep around the local actions so that we definitely run them locally.
-  if (action.action === 'TRANSIENT_ACTIONS') {
-    // Drill into the array.
-    return processActions(dispatchEvent, working, action.transientActions, spyCollector)
-  } else if (action.action === 'ATOMIC' || action.action === 'MERGE_WITH_PREV_UNDO') {
-    // Drill into the array.
-    return processActions(dispatchEvent, working, action.actions, spyCollector)
-  } else if (action.action === 'UNDO' && !History.canUndo(working.history)) {
-    // Bail early and make no changes.
-    return processActions(
-      dispatchEvent,
-      working,
-      [
-        EditorActions.addToast(
-          notice(
-            `Can't undo, reached the end of the undo history.`,
-            'NOTICE',
-            false,
-            cannotUndoRedoToastId,
+  if (shouldProcessAction) {
+    // Sidestep around the local actions so that we definitely run them locally.
+    if (action.action === 'TRANSIENT_ACTIONS') {
+      // Drill into the array.
+      return processActions(dispatchEvent, working, action.transientActions, spyCollector)
+    } else if (action.action === 'ATOMIC' || action.action === 'MERGE_WITH_PREV_UNDO') {
+      // Drill into the array.
+      return processActions(dispatchEvent, working, action.actions, spyCollector)
+    } else if (action.action === 'UNDO' && !History.canUndo(working.history)) {
+      // Bail early and make no changes.
+      return processActions(
+        dispatchEvent,
+        working,
+        [
+          EditorActions.addToast(
+            notice(
+              `Can't undo, reached the end of the undo history.`,
+              'NOTICE',
+              false,
+              cannotUndoRedoToastId,
+            ),
           ),
-        ),
-      ],
-      spyCollector,
-    )
-  } else if (action.action === 'REDO' && !History.canRedo(working.history)) {
-    // Bail early and make no changes.
-    return processActions(
-      dispatchEvent,
-      working,
-      [
-        EditorActions.addToast(
-          notice(
-            `Can't redo, reached the end of the undo history.`,
-            'NOTICE',
-            false,
-            cannotUndoRedoToastId,
+        ],
+        spyCollector,
+      )
+    } else if (action.action === 'REDO' && !History.canRedo(working.history)) {
+      // Bail early and make no changes.
+      return processActions(
+        dispatchEvent,
+        working,
+        [
+          EditorActions.addToast(
+            notice(
+              `Can't redo, reached the end of the undo history.`,
+              'NOTICE',
+              false,
+              cannotUndoRedoToastId,
+            ),
           ),
-        ),
-      ],
-      spyCollector,
-    )
-  } else if (action.action === 'SET_SHORTCUT') {
-    return {
-      ...working,
-      userState: UPDATE_FNS.SET_SHORTCUT(action, working.userState),
-    }
-  } else if (action.action === 'SET_CURRENT_THEME') {
-    return {
-      ...working,
-      userState: UPDATE_FNS.SET_CURRENT_THEME(action, working.userState),
-    }
-  } else if (action.action === 'SET_LOGIN_STATE') {
-    return {
-      ...working,
-      userState: UPDATE_FNS.SET_LOGIN_STATE(action, working.userState),
-    }
-  } else if (action.action === 'SET_GITHUB_STATE') {
-    return {
-      ...working,
-      userState: UPDATE_FNS.SET_GITHUB_STATE(action, working.userState),
-    }
-  } else if (action.action === 'SET_USER_CONFIGURATION') {
-    return {
-      ...working,
-      userState: UPDATE_FNS.SET_USER_CONFIGURATION(action, working.userState),
+        ],
+        spyCollector,
+      )
+    } else if (action.action === 'SET_SHORTCUT') {
+      return {
+        ...working,
+        userState: UPDATE_FNS.SET_SHORTCUT(action, working.userState),
+      }
+    } else if (action.action === 'SET_CURRENT_THEME') {
+      return {
+        ...working,
+        userState: UPDATE_FNS.SET_CURRENT_THEME(action, working.userState),
+      }
+    } else if (action.action === 'SET_LOGIN_STATE') {
+      return {
+        ...working,
+        userState: UPDATE_FNS.SET_LOGIN_STATE(action, working.userState),
+      }
+    } else if (action.action === 'SET_GITHUB_STATE') {
+      return {
+        ...working,
+        userState: UPDATE_FNS.SET_GITHUB_STATE(action, working.userState),
+      }
+    } else if (action.action === 'SET_USER_CONFIGURATION') {
+      return {
+        ...working,
+        userState: UPDATE_FNS.SET_USER_CONFIGURATION(action, working.userState),
+      }
     }
-  }
 
-  if (action.action === 'UPDATE_TEXT') {
-    working = UPDATE_FNS.UPDATE_TEXT(action, working)
-  }
+    if (action.action === 'UPDATE_TEXT') {
+      working = UPDATE_FNS.UPDATE_TEXT(action, working)
+    }
 
-  if (action.action === 'TRUNCATE_HISTORY') {
-    working = UPDATE_FNS.TRUNCATE_HISTORY(working)
-  }
+    if (action.action === 'TRUNCATE_HISTORY') {
+      working = UPDATE_FNS.TRUNCATE_HISTORY(working)
+    }
 
-  if (action.action === 'START_POST_ACTION_SESSION') {
-    working = runExecuteStartPostActionMenuAction(action, working)
-  }
+    if (action.action === 'START_POST_ACTION_SESSION') {
+      working = runExecuteStartPostActionMenuAction(action, working)
+    }
 
-  if (action.action === 'EXECUTE_POST_ACTION_MENU_CHOICE') {
-    working = runExecuteWithPostActionMenuAction(action, working)
-  }
+    if (action.action === 'EXECUTE_POST_ACTION_MENU_CHOICE') {
+      working = runExecuteWithPostActionMenuAction(action, working)
+    }
 
-  if (action.action === 'CLEAR_POST_ACTION_SESSION') {
-    working = runClearPostActionSession(working)
-  }
+    if (action.action === 'CLEAR_POST_ACTION_SESSION') {
+      working = runClearPostActionSession(working)
+    }
 
-  if (action.action === 'UPDATE_PROJECT_SERVER_STATE') {
-    working = runUpdateProjectServerState(working, action)
-  }
+    if (action.action === 'UPDATE_PROJECT_SERVER_STATE') {
+      working = runUpdateProjectServerState(working, action)
+    }
 
-  // Process action on the JS side.
-  const editorAfterUpdateFunction = runLocalEditorAction(
-    working.unpatchedEditor,
-    working.unpatchedDerived,
-    working.userState,
-    working.workers,
-    action as EditorAction,
-    working.history,
-    dispatchEvent,
-    spyCollector,
-    working.builtInDependencies,
-    working.collaborativeEditingSupport,
-    working.projectServerState,
-  )
-  const editorAfterCanvas = runLocalCanvasAction(
-    dispatchEvent,
-    editorAfterUpdateFunction,
-    working.unpatchedDerived,
-    working.builtInDependencies,
-    action as CanvasAction,
-  )
-  const editorAfterNavigator = runLocalNavigatorAction(
-    editorAfterCanvas,
-    working.unpatchedDerived,
-    action as LocalNavigatorAction,
-  )
-  const withPossiblyClearedPseudoInsert = maybeClearPseudoInsertMode(
-    editorStoreUnpatched.unpatchedEditor,
-    editorAfterNavigator,
-    action,
-  )
+    // Process action on the JS side.
+    const editorAfterUpdateFunction = runLocalEditorAction(
+      working.unpatchedEditor,
+      working.unpatchedDerived,
+      working.userState,
+      working.workers,
+      action as EditorAction,
+      working.history,
+      dispatchEvent,
+      spyCollector,
+      working.builtInDependencies,
+      working.collaborativeEditingSupport,
+      working.projectServerState,
+    )
+    const editorAfterCanvas = runLocalCanvasAction(
+      dispatchEvent,
+      editorAfterUpdateFunction,
+      working.unpatchedDerived,
+      working.builtInDependencies,
+      action as CanvasAction,
+    )
+    const editorAfterNavigator = runLocalNavigatorAction(
+      editorAfterCanvas,
+      working.unpatchedDerived,
+      action as LocalNavigatorAction,
+    )
+    const withPossiblyClearedPseudoInsert = maybeClearPseudoInsertMode(
+      editorStoreUnpatched.unpatchedEditor,
+      editorAfterNavigator,
+      action,
+    )
 
-  let newStateHistory: StateHistory
-  switch (action.action) {
-    case 'UNDO':
-      newStateHistory = History.undo(working.unpatchedEditor.id, working.history, 'no-side-effects')
-      working.postActionInteractionSession = null
-      break
-    case 'REDO':
-      newStateHistory = History.redo(working.unpatchedEditor.id, working.history, 'no-side-effects')
-      break
-    case 'NEW':
-    case 'LOAD':
-      const derivedState = deriveState(
-        withPossiblyClearedPseudoInsert,
-        null,
-        'unpatched',
-        unpatchedCreateRemixDerivedDataMemo,
-      )
-      newStateHistory = History.init(withPossiblyClearedPseudoInsert, derivedState)
-      break
-    default:
-      newStateHistory = working.history
-      break
-  }
+    let newStateHistory: StateHistory
+    switch (action.action) {
+      case 'UNDO':
+        newStateHistory = History.undo(
+          working.unpatchedEditor.id,
+          working.history,
+          'no-side-effects',
+        )
+        working.postActionInteractionSession = null
+        break
+      case 'REDO':
+        newStateHistory = History.redo(
+          working.unpatchedEditor.id,
+          working.history,
+          'no-side-effects',
+        )
+        break
+      case 'NEW':
+      case 'LOAD':
+        const derivedState = deriveState(
+          withPossiblyClearedPseudoInsert,
+          null,
+          'unpatched',
+          unpatchedCreateRemixDerivedDataMemo,
+        )
+        newStateHistory = History.init(withPossiblyClearedPseudoInsert, derivedState)
+        break
+      default:
+        newStateHistory = working.history
+        break
+    }
 
-  return {
-    unpatchedEditor: withPossiblyClearedPseudoInsert,
-    unpatchedDerived: working.unpatchedDerived,
-    strategyState: working.strategyState, // this means the actions cannot update strategyState – this piece of state lives outside our "redux" state
-    postActionInteractionSession: working.postActionInteractionSession,
-    history: newStateHistory,
-    userState: working.userState,
-    workers: working.workers,
-    persistence: working.persistence,
-    saveCountThisSession: working.saveCountThisSession,
-    builtInDependencies: working.builtInDependencies,
-    projectServerState: working.projectServerState,
-    collaborativeEditingSupport: working.collaborativeEditingSupport,
+    return {
+      unpatchedEditor: withPossiblyClearedPseudoInsert,
+      unpatchedDerived: working.unpatchedDerived,
+      strategyState: working.strategyState, // this means the actions cannot update strategyState – this piece of state lives outside our "redux" state
+      postActionInteractionSession: working.postActionInteractionSession,
+      history: newStateHistory,
+      userState: working.userState,
+      workers: working.workers,
+      persistence: working.persistence,
+      saveCountThisSession: working.saveCountThisSession,
+      builtInDependencies: working.builtInDependencies,
+      projectServerState: working.projectServerState,
+      collaborativeEditingSupport: working.collaborativeEditingSupport,
+    }
+  } else {
+    return working
   }
 }