In this paper, I discuss Michael Moore’s and Jonathan Schaffer’s views on the ontology of omissions in context of their stances on the problem of omissive causation. First, I consider, from a general point of view, the question of the ontology of omissions, and how it relates to the problem of omissive causation. Then I describe Moore’s and Schaffer’s particular views on omissions and how they combine with their stances on the problem of omissive causation. I charge Moore and Schaffer (...) with inconsistencies and insufficiencies within their overall theories, and consider their replies. Finally, I propose my own view on the ontology of omissions and solution to the problem of omissive causation. (shrink)