Jurgen Habermas is the author of one of the most comprehensive, ambitious and debated projects in social theory of the twentieth century. Yet his books and articles are not always easily accessible, even to those with prior knowledge of his theories. This book provides an illuminating and comprehensive overview of Habermas' work. It explores the way in which his theories have developed and changed in the last twenty years, leading to an exposition of his more complex ideas and theories. His theory of communicative action is analyzed, as are key themes, such as rights, public deliberation, law and democracy, and how they inter-relate. Habermas' contribution to the theory of international relations is also discussed.