This chapter explores the relationship between philosophy and criminal law. It first describes the link between criminal law and action theory, with emphasis on the elusive notion of an action, when omissions can be interpreted as actions, actions that are voluntary, and actions that correspond to their legal descriptions. Attention then turns to the relationship between criminal law and the philosophy of mind, giving consideration to when and why a mind is deemed guilty. These considerations lead directly to the discussion of the morality of punishment, and to the analysis of retributivism and consequentialism. The chapter concludes by assessing the relationship between criminal law and political philosophy, focusing on liberalism and on the instances of wrongdoing that justify the state a in inflicting hard treatment on criminals.