This book reassesses the contribution to international thought of some of the most important thinkers of the inter-war period. It takes as its starting point E. H. Carr's famous critique which, more than any other work, established the reputation of the period as the 'utopian' or 'idealist' phase of international relations theorizing. This characterization of inter-war thought is scrutinized through ten detailed studies of such writers as Norman Angell, J. A. Hobson, J. M. Keynes, David Mitrany, and Alfred Zimmern. The studies demonstrate the diversity of perspectives within 'idealism' and call into question the descriptive and analytical value of the entire notion. It is concluded that 'idealism' is an overly general term, useful for scoring debating points rather than providing a helpful category for analysis.