Mental Means offers a systematic treatment of intentional mental action: what you do intentionally with your mind. You can think of a word to decide on a password, call to mind how something looks to imagine it, or make a judgment to answer a question. When using a mental action as a means in this way, your thoughts can take on greater significance than they would otherwise have. Just one thought can instantiate several types of thought at once, individuated by attitude and content. For instance, one thought can have two distinct propositional contents, or it can be both a judgment and a decision. Antonia Peacocke applies this idea to solve three kinds of puzzles in philosophy of mind and epistemology. First there are action puzzles, which concern the type of agency you can exercise in thought. A judgment can be made intentionally, under a certain description, and so you can exercise agency over what you believe. You can also intentionally conceive a new artistic work by refining an early draft or version. Then there are duality puzzles, which arise when a thought of some kind seems to belong to more than one content-attitude type. This book shows how this works in imagination and knowledgeable self-attribution of belief. Finally, there are process puzzles, which concern the relationship of individual thoughts to ongoing mental processes. The use of mental means clarifies the role of individual judgments in inference and in inquiry. The solutions to these puzzles all emerge from an original foundational theory of intentional action and the practical knowledge it involves.