This paper studies secrecy practices within transnational think tanks. Drawing on ethnographic data from three such organisations, we explore how everyday practices undertaken in secrecy amount to discreet diplomatic efforts. We suggest that transnational think tanks should be understood as “shutter boxes” that engage in three types of secrecy practices: shadowed, hidden, and conspicuously shown. Although outwardly striving for transparency, secrecy practices are vital for transnational think tanks as they strive to establish themselves as actors of consequence in foreign relations and diplomatic circles. Practices of secrecy are part and parcel of the power game played by think tanks, in which all participants learn and master what to discuss and what not to display.