The Tunisian General Labor Union (UGTT) played a major role in the 2010/11 Tunisian revolution and in the subsequent democratization process. This article seeks to explain why the union was capable of taking on this role in light of the fact that, before the revolution, it cooperated with and was heavily infiltrated by the regime of President Zine El-‘Abidine Ben ‘Ali. By describing the UGTT’s internal struggles during the dictatorship, the article claims that the UGTT demonstrated elements of both resistance and compliance. This duality made it possible for the organization to survive authoritarianism and also be a credible player in the transition to democracy. The article shows, in contrast to the dominant theories within democratization studies, that a regime-affiliated civil society organization can play an important role in the democratization process.