Th is volume brings together a series of essays addressing how we are to understand and justify laws prohibiting discrimination—both laws that apply in the public sector, providing rights to some form of equal treatment by governments or other public authorities, and laws that apply in the private sector, providing rights to non-discrimination by private organizations in contexts such as the provision of employment, accommodation, and education. Such laws raise many daunting philosophical questions. Indeed, part of what makes this area of law such a diffi cult one is that there is no initial agreement among scholars as to what the important questions are. One aim of the chapters in this volume is to try to demonstrate that certain questions are worth investigation, and so to help shape our future collective discussions about discrimination law. Th e other aim, of course, is to defend certain answers to these questions. Th is is a relatively young fi eld of inquiry, refl ecting the fact that most antidiscrimination laws are relatively new. Although a few countries, such as the U.S., have had longstanding constitutionalized equality rights, it is arguably only since World War II that these constitutional rights have been interpreted in a broad way so as to recognize that all citizens have certain rights to non-discrimination 1 ; and it is also only post World War II that most countries have enacted domestic civil rights codes protecting individuals from discrimination in the private sector. 2 It is not surprising, then, that our theorizing about discrimination laws is also at an early stage.