Defining animation once, then repeating across a selection of shapes in a cascading manner? I have a comp with 20 windows (for a building), that I want to animate in a cascading manner (i.e. windows 1 though 20) with half a second in between each window animates in.

Is there a way for me to define the animation once (i.e. scale from 0 to 100 and increase opacity from 0 to 100), then to apply it to all shapes with a defined space between each animation starting?

Thanks,
Andy.
Assuming the same thing happens in each window...
Make the action that will be inside the first window in its own comp.
Then duplicate the comp 19 times, and use something like the brilliant pt_shiftlayers script to stagger each of the layers half second after the previous one.