This book is concerned with the study of collective preference, in particular with the relationship between the objectives of social action and the preferences and aspirations of society's members. Professor Sen's approach is based on the assumption that the problem of collective choice cannot be satisfactorily discussed within the confines of economics. While collective choice forms a crucial aspect of economics, the subject pertains also to political science, the theory of the state, and to the theory of decision procedures. The author has therefore used material from these disciplines, plus philosophical aspects from ethics and the theory of justice.