This is the first book devoted to the work of Peter Singer, one of the leaders of the practical ethics movement, and one of the most influential philosophers of the twentieth century. Singer’s metaethical views, his normative theory, and his substantive positions on such matters as the moral status of animals, the sanctity of human life, and famine relief are all subjected to scrutiny. This volume contains new essays by leading philosophers from three continents: Richard J. Arneson, Roger Crisp, Lori Gruen, Richard Holton, Frank Jackson, Dale Jamieson, F. M. Kamm, Rae Langton, Colin McGinn, Rolmes Rolston III, Michael Smith, and Robert Solomon. R. M. Hare’s previously published rejoinder to Singer, Why I Am Only a Demi-Vegetarian is also included. Singer’s replies to his critics importantly supplement what he has previously written and will be essential reading for anyone who wants to fully understand his views.