In 1980, at the end of the most intensely political period of his work and life, Louis Althusser penned Philosophy for Non-philosophers. Available here for the first time in English, Philosophy for Non-philosophers constitutes a rigorous and engaged attempt to address a wide reading public unfamiliar with Althusser's project. As such, the work is a concentration of the most fundamental theses of Althusser's own ideas, and presents a synthesis of his sprawling and disparate philosophical and political writings. Nowhere else does Althusser push the distinction between philosophy and other disciplines as far, or develop in such detail the concept of 'practice'. Rather than a work of 'popular philosophy', Philosophy for Non-philosophers is a continuation and conglomeration of Althusser's thought; a thought whose radicality is still perceptible in those that have followed since. Philosophy for Non-philosophers thus provides a vivid encapsulation of Althusser's seminal influence on the leading thinkers of today, including Ranciere, Badiou, Balibar, and Žižek.