In English, the causation verbs make and let allow their following VP to be omitted; e.g. "I made/let Chris play the drums before I made/let Sam (play the drums)". We show that such ‘causative VP-omission’ involves Null Complement Anaphora rather than predicate ellipsis, and for most speakers requires an agentive causee. Examination of aspectual verbs suggests that the agent restriction extends to Null Complement Anaphora in general.