This essay offers an action-theoretic analysis of the distinction between positively bringing something about and passively letting something happen. The analysis, based on the notion of an agent''s bringing about some state of affairs, is closest to the analysis of omissions of Brand (1971), but utilizes the relatedness logic of Epstein (1979). Syntactic features bring out the idea that an action can be partially positive and partially negative, e.g., by not bringing about one thing an agent can bring about something (...) else. An ethical implication of this analysis is that a passive course of action is sometimes less culpable than an active one, just because it is passive. (shrink)