ABSTRACT As the third-largest exporting country in the world, Germany is a clear beneficiary and proponent of free trade. Few, therefore, expected the magnitude of contention that emerged within Germany during the negotiations between the EU and the United States for a transatlantic trade deal (TTIP). This paper explores the politicisation process of TTIP within the context of the broader transformations of German politics including not only the entry of new issues and new players in the electoral and protest arenas but also the increased hybridisation of forms of protest. Theoretically, we draw on the ‘Players and Arenas’ framework to put forward a sequential, strategic interactionist approach to the unfolding process of politicisation, in which various types of players face dilemmas when interacting with each other over time. Applying this analytical framework to the politicisation of TTIP in Germany, we reveal previously overlooked players, interactions and dilemmas, while opening up multiple opportunities for empirical analysis of cases beyond this area. We show how the politicisation of TTIP brought about an important intensification of relations between Germany’s protest and electoral arenas, and confronted all players involved with choices with long-lasting consequences for both mobilisation and coalition building dynamics.