This article uses new evidence from the former archive of the Ministry of State Security (Stasi) of the German Democratic Republic to show that important intelligence was gathered by Western intelligence agencies, above all those of the United States, from well-placed human sources in the GDR's economy during the first twenty years of the Cold War. This intelligence influenced policymakers' understanding of the GDR's economy and informed debates about weapons procurement and the best trade, credit, information, and aid policies to pursue vis-à-vis the GDR and the Soviet bloc. The intelligence obtained from spies in the GDR's economic bureaucracy and industrial enterprises declined in quality from the 1960s on because of effective counterintelligence measures adopted by the Stasi. The loss of this information contributed to Western policymakers' failure in the 1980s to grasp the full extent of the economic crisis in the GDR that helped to precipitate the Communist regime's collapse.