The principal aim of my thesis is to provide a unified theory of imagining, that is, a theory which aspires to capture the common nature of all central forms of imagining and to distinguish them from all paradigm instances of non-imaginative phenomena. The theory which I intend to put forward is a version of what I call the Agency Account of imagining and, accordingly, treats imaginings as mental actions of a certain kind. More precisely, it maintains that imaginings are mental (...) actions that aim at the formation of episodic representations, the content of which is directly determined by what we want them to represent. My defence of this version of the Agency Account happens in two stages. On the one hand, I try to show that it is both extensionally adequate and explanatorily illuminating with respect to those mental states or projects which are clear instances of either imaginative or non- imaginative phenomena. And on the other hand, I seek to demonstrate that the most plausible alternative to the Agency Account - namely the Cognitive Account according to which it is distinctive of imaginings that they are non-cognitive phenomena and thus to be contrasted with perceptions, judgements, and so on - is bound to fail as a unified theory of imagining. The dissertation contains five main parts. In the first, I specify in more detail what a unified account of imagining has to achieve and, in particular, which phenomena it is supposed to capture. The second part presents the Cognitive Account, thereby focussing on Brian O'Shaughnessy's sophisticated version of it while the third part is reserved for the evaluation and rejection of the Cognitive Account. In the fourth part, I develop my version of the Agency Account of imagining. And the fifth and last part is concerned with the accommodation of potential counterexamples to it. (shrink)