Ideologies play a crucial role in the way we understand and shape the political world. But no one has satisfactorily explained the nature of ideologies themselves. In his important new book, Michael Freeden offers a ground-breaking approach to the subject. Drawing on the political experience of Britain, France, Germany, and the USA over the past two centuries, the author provides an in-depth examination of the key political ideologies: liberalism, conservatism, socialism feminism, and green political thought. He goes on to outline a powerful and sophisticated new theory of ideologies and argues that by paying special attention to the complexity, conceptual inter-relationship, and historical and contemporary context of ideologies we can both better understand them and reinvigorate the study of political theory.