You can assign them any ID you'd like as long as they don't conflict with other dialog controls IDs. When you use a dialog template resource to create controls, VS does this automatically for you and keeps track of them in the resource.h file. You can add a range of your own IDs to this file using the "Resource Symbols" wizard. You can access this from the "Resources" tab by right-clicking on the <YourAppName>.rc entry and selecting "Resource Symbols".