This thesis examines the relationship between the security service of East Germany and its allies in the Soviet Union and Czechoslovakia during the Cold War, from 1948–89. My use of international history to analyse intelligence-sharing takes us beyond the hierarchical models that typically characterise collaboration and challenge any notion that peripheral Warsaw Pact states were in awe of the Moscow centre. Instead I show that the services were mutually constructed. I analyse how the East German Ministry for State Security (Stasi) sought to cooperatively establish structures to govern intelligence-sharing processes with the Soviet Committee for State Security (KGB) and the Czechoslovakian State Security Service (StB), so that domestic security needs were balanced with the broader alliance’s objectives for collaboration. The tension between national interests and transnational obligations was felt acutely in East Germany and Czechoslovakia. I examine how such tensions were reconciled and, conversely, the effects of failed reconciliation efforts in order to understand the complexities of intelligence collaboration. My research predominantly addresses these questions in relation to the transfer of foreign intelligence. This approach leads me to new sites of intelligence diplomacy as I examine East German diplomacy in the developing world, particularly Zanzibar, and invites reconsideration of old themes, including the Stasi’s role in the 1983 War Scare.