The key of working with threads are sychonizing mechanisms. A common one is a Semaphore. As you may know, a semaphore is basically a shared resource handler that flags an object as used or unused to prevent other threads from trying to use it at the same time. It isn't automatic, your program has to lock a resource and unlock it when it's done. You can use this in combination with a process flag to indicaate the status of a task being done. Look up semaphores in your references or on the net. I think you will find excatly what you are looking for there. Now I'm assuming that all the process you are refering to are in the same program. If it's two seperate programs, you'll have to adapt this concept with a shared resource accessible from both programs. Hope that helps get you started.