Peter van Inwagen, author of the classic book An Essay on Free Will (1983), has established himself over the last forty years as a leading figure in the philosophical debate about the problem of free will. This volume presents eleven influential essays from throughout his career, as well as two new and previously unpublished essays, 'The Problem of Fr** W*ll' and 'Ability'. The essays include discussions of determinism, moral responsibility, 'Frankfurt counterexamples', the meaning of 'the ability to do otherwise', and the very definition of free will, as well as critiques of writings on the topic by Daniel Dennett and David Lewis. An introduction by the author discusses the history of his thinking about free will. The volume will be a valuable resource for those looking to engage with van Inwagen's significant contributions to this perennially important topic.