This book provides students with a comprehensive and systematic introduction to political theories and ideologies of the 19th and 20th centuries. The text is organized into four parts. Part I describes the leading ideologies of the twentieth century. Part II describes the totalitarian ideologies of the twentieth century. Part III deals with the three ideologies that have dominated the politics of democratic societies in the twentieth century. Part IV examines three nascent ideologies that are becoming increasingly potent political forces. In the concluding chapter entitled Beyond Ideologies various versions of the end of ideology theory are considered.