The notion of obligation of what an agent owes to himself, to others, or to society generally occupies a central place in morality. But what are the sources of our moral obligations and what are their limits? To what extent do obligations vary in their stringency and severity, and does it make sense to talk about imperfect obligations, that is, obligations that leave the individual with a broad range of freedom to determine how and when to fulfil them? The twelve essays in this volume address these and other questions and explore related issues. Some of them discuss broad theoretical questions, some essays look at moral reasons for action. Others discuss specific moral obligations or the tensions that may exist between our obligations and our other concerns.