Thanks for the reply (again)!

I've since been working through the Lynda.com AS videos and have learned a little more since I posted.

I would like to have 8 (for example) objects (movie clips) in the library.

On an event, mouse or frame enter (for example), 4 of those objects from the library are displayed on the screen, chosen at random.

So it would be:
On frame enter, choose 4 movie clips from a list of 8 and make them visible on the stage.

Thanks!