In this book, Sven Bernecker investigates the defining characteristics of memory and the issues essential to understanding it. The book gives a comprehensive philosophical account of memory and illuminates issues central to contemporary discussions of metaphysics and epistemology such as personal identity, causation, mental content, and justification. Bernecker argues that remembering something, unlike knowing something, does not require having a belief. There are also instances where one has a memory but no justification for what one remembers. These surprising results suggest that remembering something requires standing in an appropriate causal relation to the relevant past representation. The book shows that a distinction needs to be made between the causal dependence of a memory on a past representation and the causal dependence of a memory on that which retains the past representation. This distinction turns out to be crucial for discerning cases of remembering from instances where some content is learned anew rather than recalled. The book proposes a theory of memory contents whereby they are determined by relations the subject bears to his past physical or social environment rather than by states internal to the subject. This theory is shown to be compatible with the compelling psychological criterion of personal identity. Against the background of the theory of memory contents, Bernecker maintains that a memory content need not be the same as, but only similar to, the content of the representation from which it causally derives. This view has interesting results for the debate over false memories and the theory of self-knowledge.