Since the riots on the occasion of the anti-G20 protests in July 2017, the radical left has received increased media attention. In the course of this, fundamental questions about the backgrounds, actors and networks of left militancy are raised: Who are 'the Autonomous'? What is 'the Antifa'? Question marks usually outweigh the certainties. The radical left, in its most varied, often competing forms and cycles, has been an actor in political disputes since the origins of liberal democracy. Avoiding security and regulatory policy as well as affirmative-sympathetic short circuits, this anthology aims to provide orientation with the help of historical longitudinal sections, country and case studies as well as highlight approaches to present-day phenomena. The guiding basic motif of the tape is the desire for objectification and differentiation.