This dissertation is a study of the problem of beliefs about oneself, or so-called de se beliefs: for example, the beliefs that I would express by saying 'I am left-handed' or 'I am in Massachusetts'. The problem arises against the background conception of belief as a propositional attitude, i.e., as a relation between conscious subjects and abstract entities that are either true or false absolutely. ;Many philosophers have recently argued that the intentional objects of one's de se beliefs could not (...) be propositions: since, e.g., I can believe the proposition that Neil Feit is left-handed without believing myself to be left-handed , and I can believe any proposition expressed by a sentence of the form 'the F is left-handed'--where 'the F' is a qualitative description--without believing myself to be left-handed . ;I take the position that the argument is sound, and, after surveying various attempts to solve the problem, I defend the self-ascription view of belief: viz., the view that to have a belief is to ascribe a property to oneself. For example, I believe that I am left-handed simply by self-ascribing the property of being left-handed. ;I defend the view against various objections to it, discuss its relations to other views about the objects of belief and the other attitudes, and maintain that it can account for the acceptance of propositions and for beliefs about particular individuals as well as for beliefs directly about oneself. I argue that belief states are best taken to be self-ascribed properties, and try to solve some problems about de re belief from the perspective of the self-ascription view. (shrink)