This volume brings together the most significant articles which have appeared over the past three decades analyzing the application and effects of price discrimination. Discrimination is a pervasive marketing practice that survives despite the attempts of regulators to limit or eliminate its use; it is widespread also in oligopolistic and imperfectly competitive markets. It is a practice used by firms in pricing their products over product dimensions such as space, time and quality, and it affects the ability of firms to compete in other firms' markets or to protect their own. This collection of articles by leading authors in the field highlights what we know of the motivations for and the welfare implications of price discrimination. It also presents a blueprint for further work in this important area.