This book provides a systematic, philosophically informed account of criminal responsibility. Part 1 of the book provides an innovative account of some of the underlying principles of criminal responsibility in the context of political theory, showing how the conditions of responsibility are articulated in, and restrained by, the institutional setting of the criminal law. Part 2 uses the insights developed in Part 1 to reconsider some of the central doctrines of criminal responsibility, examining issues including the nature of causation, intentions, and beliefs, and mental disorder defences, excuses, and justifications.