The highly commended First Edition of this four-volume set remains the standard reference on Jürgen Habermas, the key theorist of the Frankfurt School and one of the most influential theorists of the twentieth and twenty-first centuries. With Habermas having developed his oeuvre substantially in the last decade, this new edition retains the key secondary literature while refreshing the critical canon with the most important papers published since the First Edition in 2001. The editors, themselves a part of that canon, have updated the editorial material to reflect the latest hot topics in the study of this perennially relevant theorist.