Straddling, linking, and blurring the distinction between the categories of ‘civil’ and ‘political’ society, labor movements and trade unions have been relatively neglected in the study of Middle Eastern and North African politics in favor of scholarly focus on states, militaries and elites, rentier economies, identity politics, and Islamic movements. Taking as its primary case study the Tunisian General Labor Union (UGTT), we draw on extensive recent fieldwork to argue that under appropriate conditions, trade unions and labor movements can acquire sufficient power and material resources to operate as leading political actors during periods of ‘transition’, and political change more generally. Our analysis focuses on four specific features of the UGTT, features that are the conditions of possibility of its political agency. First, its extensive and longstanding organizational structure allows it to initiate, frame, and control collective action through the organization and mobilization of the labor force. Second, it possesses major economic and social clout, giving it leverage to pressure and enforce change on the ruling regime. Thirdly, at moments of political upheaval, it has drawn on its mastery of the art of negotiation and mediation to act as an effective arbitrator between different political factions. Lastly, representing members from diverse ideological, social, and religious backgrounds, its heterogeneity gives it legitimacy across the population in a way no political party can rival. The influence of the UGTT, we argue, as a potent actor both purportedly above politics and profoundly political, accounts in large part for the relative success of the Tunisian revolution as opposed to other contemporary Middle Eastern uprisings, as well as for many of the inadequacies of post-revolutionary politics.