I know this would have helped me, maybe it would others. In the documentation on Deferred's in the howto section, the examples that show a blocking operation and then a non blocking operation do not show what happened to the blocking code, it just conveniently disappears. For someone new to async programming it might help to give an example that shows the blocking code being called via deferToThread. In other words show how you would handle blocking code. It doesn't matter if there are 10 ways of doing it, just one example I think would go a long ways to illustrating the complete idea. I know when I was reading about Deferreds for the first time, I was sitting there thinking 'Ok, I know the example doesn't block now because they just conveniently yanked out the blocking code!!, but what DID they do with it?' Chris