Hi David, Yes, the process is called rotoscoping. The animated content simply needs to have an embedded alpha channel to prevent "showing" the particle itself. You'll get the best results using the Splat particle option. To get truly good results you'll need to get a handle on the Particle Shader to control some of your effects. This is one of the least used and most powerful features of Carrara. It's possible to create some absolutely excellent effects. I've done this quite a lot of this type of work on various assignments for smoke and snow in fact. Works great. Post back with any questions. I recently helped a film producer create some outstanding oily smoke with particles. Really fun stuff. Mark