Tunisia’s labor union UGTT was praised for its important political role in the country’s transformation process. At times it built up pressure against parts of the political elite, at other times it offered ways for consensus and cooperation between different factions. Yet, its social role since 2011 has not received as much attention. In this paper I show that a closer analysis reveals different roles that touch upon questions of social justice and stability, and thus on the overall transformation process. First, the UGTT helped by expressing socioeconomic demands in form of public protests, not only of workers but also in cooperation with other forms of civic activism. Second, it helped by mediating between protests outside its framework and state representatives, by channeling the demands into the political system or facilitating negotiations. Third, in many cases its action aimed at stopping and preventing informal protests when they were perceived as harmful to worker interests and to public order. The analysis builds on field research conducted in 2014 and 2015 and highlights challenges for the labor union, both as the representation of the formal labor sector, and as being couched between the broad informal, increasingly contentious sectors of society and the political system.