This book analyses all relevant questions of State responsibility and attribution arising from the conduct of rebels and governments in the context of civil wars and rebellions aiming at the establishment of a new government or the creation of a new State. Based on a comprehensive analysis of both old and recent State practice, and case law, including investment awards, as well as the works of scholars and the International Law Commission, the book identifies ten basic rules which can be used by States and international tribunals. It explains the history, content and scope of application of the specific solutions adopted in Article 10 of the International Law Commission Articles on State responsibility to address particular problems. The book also critically revisits some of the solutions that have been put forward by tribunals and scholars, and examines a number of questions which have never been addressed by them before.