This textbook provides a survey of the literature of social choice. It integrates the ethical aspects of the subject, (discussing potentially desirable conditions for social judgements) with positive aspects of decision mechanisms that centre on the revelation of true preferences. The literature on the subject presently consists of a great many papers. This book draws them together in common notation and points out interpretations which are often missing in specialist papers. Applications in economics, electoral politics, and ethics are discussed. The book will be used by senior undergraduate and graduate students of economics, political science and philosophy as a text book in the subject.