Who decides about the promotion of social objectives in EU’s trade policies? The existing literature oscillates between giving emphasis to the EU Commission or to interest group lobbying. Both approaches have limitations. To overcome those limitations, I here revisit the EU history of promoting labour provisions at the bi – and multilateral trade levels between 1993 and 2016. I argue that the EU Commission acts in line with the political positions and preferences of EU constituents on trade-labour linkage and that its autonomy depends on how polarized and salient those positions are. After finding evidence in line with that argument, I conclude that EU principals are ultimately in control of the link between trade and social objectives in EU trade policy and that the autonomy of the Commission, although existent, is limited. This article applies nuance to arguments centred on the power of the Commission to promote its own preferences at the expense of its constituents’. In doing so, it also contributes to understanding the politics of the design of social and sustainable development provisions in EU trade agreements.