E. H. Carr's classic work on international relations published in 1939 was immediately recognized by friend and foe alike as a defining work. The author was one of the most influential and controversial intellectuals of the 20th century. The issues and themes he developed continue to have relevance to modern day concerns with power and its distribution in the international system. Michael Cox's critical introduction provides the reader with background information about the author, the context for the book, and its main themes and contemporary relevance.