So, this is all hypothetical. This isn't really anything I am trying to do at the moment, but what I want to know is how to keyframe constraints. Example: Say I have an item that - at some point in the animation - needs to be picked up by a character. (e.g. the item could be a sandwich.) Is there any way to initialize a 'child-of' constraint type and have it become inactive or dormant at points in the animation? If you had a character with a constrained item object, then it would seem reasonable for him to have a need within your plot to put the item down and not have that item drag along behind him every time he moved his hand like a puppet tied to his finger with an invisible thread.