Apple or pears? Guns or butter? Liberty or death? We experience life as a series of choices, large and small. What makes a choice rational? A common answer is that a rational agent calculates the probable net benefits of each possible course of action and chooses the one that best satisfies his or her given preferences. Rational choice is thus about means, not ends, a view which has been most deeply analysed in economic, and that is now becoming crucial throughout the social sciences. The Theory of Choice provides an authoritative and comprehensive introduction to the fundamental principles of rational choice theory, game theory, and to their implications and limitations. The book is in three parts with a section of keywords. Part I covers individual choice, analyzing the theory of decision making by an individual who need not consider the effect on other people's decisions. This includes the study of rationality, consumer theory and autonomy. Part II examines interactive choice in which the actions taken by one person depend on, and influence, those taken by others. The modern key to understanding such situations is game theory. The final part covers collective choice where individuals group together to agree a common strategy or policy, which is then implemented. This section includes surveys of social choice, democracy, power and social justice. Finally, the Keywords section contains notes on the major concepts, technicalities and thinkers. The Theory of Choice is the result of collaboration between three economists, a philosopher and a political scientist. It will become essential reading for students across a range of disciplines and for professional social scientists wanting a lively introduction to these important ideas.