This course introduces students to rational actor theories of politics. These theories consider how people make choices in different political environments and the effect of these choices on interest groups and political parties. Would you expect people to be less selfish or more selfish in politics? Do people join interest groups because of their commitment to social ideals or because of what they get from the group? Why do groups fail to achieve goals even when the achievements of these goals are likely to benefit everyone in the group? The material in this course is useful for students interested in mass politics or grassroots organizing, since we discuss the main variables influencing successful collective actions.