The present study aims to characterize the impact of American think tanks’ specific position – at the crossroads between the academic and the political worlds – on their discourse. It offers a structural and rhetorical analysis of a corpus of policy briefs published by three think tanks between 2010 and 2013. The following hypothesis is explored: the constraints to which think tanks’ experts are submitted in their everyday practices due to their position, and the resulting tension between expertise and political action, are reflected in the genre. Results show that the structure of policy briefs is extremely codified since it is organized in response to policymakers’ demands for external expertise. However, an analysis of the genre’s rhetorical phenomena highlights its programmatic aim, as think tanks offer expertise but also seek to convey their agenda to the political world. Policy briefs thus seem characterized by a hybrid dimension which sheds light on the nature of the expertise offered by American think tanks.