Introduction: the international Red Cross and Red Crescent Movement and the development of international humanitarian law Stefanie Haumer, Robin Geiss and Andreas Zimmermann; Part I. The International Committee of the Red Cross' Influence on the Development of Core International Humanitarian Law Treaties: 1. The International Committee of the Red Cross and the Geneva Conventions of 1949 Robert Heinsch; 2. The International Committee of the Red Cross and the additional protocols of 1977 Michael Bothe; Part II. The International Committee of the Red Cross and the Development of International Humanitarian Law beyond Treaty Regimes: 3. The International Committee of the Red Cross and the clarification of customary international humanitarian law Jean-Marie Henckaerts; 4. The International Committee of the Red Cross' 'interpretive guidance on the notion of direct participation in hostilities': see a little light Robert Cryer; Part III. The International Committee of the Red Cross' Influence on Related Areas of International Law: 5. Development of treaties limiting or prohibiting the use of certain weapons: the role of the International Committee of the Red Cross Kathleen Lawand and Isabel Robinson; 6. Between 'constructive engagement', 'collusion' and 'critical distance': the International Committee of the Red Cross and the development of international criminal law Carsten Stahn; Part IV. Conclusion: 7. The International Committee of the Red Cross – a unique actor in the field of international humanitarian law creation and progressive development Robin Geiss and Andreas Zimmermann.