During the period between the two world wars, the Independent Labour Party was the main voice of radical socialism in Great Britain. Founded in 1893, the ILP had affiliated to the Labour Party in 1906, when that party formed, although relations between the two had often been marked by conflict. In the decade following World War I, as the Labour Party edged nearer to its 1929 electoral victory, the ILP found its own identity under siege. On one side stood those who wanted the ILP to subordinate itself to the increasingly cautious and conventional Labour Party. On the other side were those who felt that the ILP should throw its lot in with the newly formed Communist Party of Great Britain and affiliate with the Soviet Communist Party. In 1932, the ILP chose instead to disaffiliate from the Labour Party in order to pursue a “revolutionary policy”—a policy that ultimately led to much debate and disunity. At the time it broke with Labour, the ILP boasted a membership five times that of the CPGB, as well as a sizeable contingent of MPs. By the return of war in 1939, the party had all but dissolved. Despite its reversal of fortunes, during the 1930s—years that witnessed the ascendancy of both Stalin and Hitler—the ILP demonstrated an unswerving commitment to democratic socialist thinking. Drawing extensively on the ILP’s Labour Leader and other contemporary left-wing newspapers, as well as on ILP publications and internal party documents, Bullock examines the debates and ideological battles of the ILP during the tumultuous interwar period. He argues that the ILP made a lasting contribution to British politics in general, and to the modern Labour Party in particular, by preserving the values of democratic socialism during the interwar period.