Social historians of medicine and sexuality have focused in recent years upon various strands of public health policy towards sexually transmitted diseases. However, despite the fact that, from the 1930s, contact tracing became one of the primary weapons with which British government sought to contain the incidence of STDs, its history in twentieth-century Britain has been largely ignored. Based on a range of governmental and private archives, supplemented by interviews with former practitioners, this paper examines the development of contact tracing in Scotland from its origins in the interwar period, through its expansion under Defence Regulation 33B during the period 1942-7, to its postwar development within the National Health Service. Particular attention is paid to the discriminatory aspects of wartime controls and to the professional, resource, and legal constraints shaping contact tracing in postwar Scotland.