WHen does the ObjectID get set on my objects?

I have a main Entity, and a collection of "child" entities, and I add an entity to the "child collection" and none of the ObjectIDs are set.

I'm trying to figure out how to maintain "state" between postbacks to ensure that my "new" record I just added to the collection is the one I'm looking for, and I was going to use the ObjectID to accomplish that...

Thanks,

Andrew.

Object ID is created at runtime when a new entity is instantiated.