How do trade unions respond to mass uprisings against authoritarian rule? The unprecedented mass uprisings that have swept the Arab world since 2010, and unseated long-standing autocrats in Egypt and Tunisia, have surprised experts and non-experts alike. Given that workers, sometimes individually and other times as an organized force, were central actors in these uprisings, understanding their role in these transformations is crucial to understanding how revolutionary uprisings emerge. This paper seeks to explain why Egyptian and Tunisian unions have played significantly different roles in the 2010/2011 uprisings and their aftermath. While the Egyptian Trade Union Federation advised workers not to participate in the 2011 uprising, local branches of the Tunisian General Labor Union (UGTT) were central in organizing protests against former President Ben Ali and The UGTT has played mediating political role in the ensuing transition from authoritarian rule in Tunisia. A large body of research in political science, focused largely on Latin America and Europe, has sought to bring back the role of workers and trade unions, in explaining transitions from authoritarian rule. In explaining the role of unions in these transitions, scholars have pointed to two primary factors: (1) material interests; and (2) unions’ relationship with the state under authoritarian rule. A sole focus on these factors is problematic for two reasons. First, the Egyptian and Tunisian cases challenge the assumption that unions are necessarily motivated by material interests. Instead, unions in these cases were either stripped of their ability to defend their members’ material interests (Egypt) or have emerged as entities whose agenda sometimes transcends the interests of union members (Tunisia). Second, the focus on the relationship between unions and the state under authoritarian rule obscures the interaction between unions and specific organs of the state, especially ruling political parties. This paper explores an alternative explanation to those presented in the existing scholarship. I hypothesize that the context in which trade unions emerge and whether their formation precedes the establishment of ruling or loyalist parties has important long-term implications for the type of union activism in a given country. In cases where trade unions precede the formation of ruling political parties, trade unions are more likely to develop agendas independent of the ruling party. This hypothesis highlights an under-explored factor in studies of unions in authoritarian regimes, namely unions’ ties to ruling parties. The paper employs a comparative historical approach and utilizes primary sources and interviews.