In this thesis, I provide an account of differential object marking (DOM) in spoken Persian couched in the framework of Aissen (2003). In analyzing Persian indefinite patterns and their interaction with DOM in this way, I illustrate how DOM in Persian is sensitive to distinctions in definiteness that are not included in the traditional definiteness hierarchy. I argue that these distinctions concern the referential stability of the object in both current discourse contexts and in future discourse contexts. In this regard, I propose a structural distinction between partitive and epistemic specificity, which in turn has an important cross-linguistic prediction. I propose that the property of identifiability in principle also be represented in the definiteness hierarchy in which an additional distinction between strong and weak varieties of identifiability is included. Finally, I indicate how other analyses of Persian DOM that do not make reference to prominence hierarchies, but assign object marking a particular semantic denotation are problematic in the larger picture.