The ontology of non-concreta (objects that are non-concrete but possibly concrete) has traditionally been employed to make sense of Necessitism—the thesis that necessarily everything necessarily exists. In this dissertation I present other uses for non-concreta (or things that are very similar to them). They can be used to develop new views of possible worlds, material objects, the nature of the past, and God's creation of the world that help us avoid some problems concerning these issues. One forceful objection to the existence of non-concreta is that their modal properties aren't grounded in their non-modal properties. In light of this objection, I also give different ways of 'thickening' non-concreta in order to provide a grounds for their modal properties.