A proposition ontology occupies a potentially rich and foundational place in a good deal of contemporary philosophical theorizing. Some of the biggest roadblocks to a wider acceptance and employment of propositions have been legitimate worries about their nature, or ontological "explanatory" power of theories that employ them. This dissertation attempts to understand and construct a deflationary or minimalist understanding of the notion of a proposition and its theoretical roles. On the basis of this understanding, following Stephen Schiffer (2003), I attempt to construct an ontology of propositions -focusing on general propositions- which avoids or dissolves the most pressing worries about their ontological nature, and the epistemological and explanatory statuses of propositions. In chapter one, I discuss the primary theoretical motivations for positing propositions, and argue for a general set of ontological constraints that fall out of a consideration of entities posited according to these motivations. In chapter two, after arguing that propositions are substantially ontologically independent of mind and language, I argue that propositions are conceptually mind- dependent, but that conceptual dependence of this kind does not amount to any sort of ontological dependence. In chapter three, drawing heavily on the work of Stephen Schiffer (2003), I substantially address the epistemological worries about propositions, arguing that propositions are pleonastic entities whose natures and existence we can know simply by reflecting on our proposition- introducing linguistic practices. In chapter four, I argue that propositions may or may not, in virtue of their status as pleonastic entities, play any substantial explanatory role, but that by utilizing the notion of a proposition, which, according to the pleonastic conception of them, guarantees their existence independent of our practices, is useful and perhaps indispensable to certain of our communicative and epistemic practices. Our propositional linguistic practices, involving essentially our reference to propositions, are thus pragmatically justified.