ABSTRACTThis article provides a historical account of the American-supported ‘counterinsurgency’ campaign in Guatemala in the 1960s. The analysis of a selection of now-declassified secret documents and of a number of public testimonies given by representatives of the executive branch before the US Congress reveals the existence of two very different discourses on ‘counterinsurgency’ and ‘terrorism’. A focus on the profound differences between these public and secret discourses, it is argued, allows for a powerful critique of government-sponsored projects that, from Camelot in 1965 to the Human Terrain System programme launched in the mid-2000s, have attempted to harness the expertise of social scientists in the service of often extraordinarily brutal US ‘counterinsurgency’ campaigns.