In January 2014, Tunisia’s National Constituent Assembly (NCA) approved the country’s first democratic constitution by near unanimity of votes. The high approval rate which involved politicians representing leftist, centrist, Arab nationalist, Islamist and secularist inclinations who held diverging views on the organization of politics following the 2010/11 popular uprising gained Tunisia a ranking of “free” by the Freedom House in 2015, certifying its democratic change. It also set the country apart from nearby Egypt, where the 2012 constitutional disagreement was seen as a prelude to the military’s intervention in politics in the following year (El-Shobaki, 2014). Recent accounts of the Tunisian post-revolution political pact have pointed to role of the political elites’ commitment to dialogue and compromise, their previous experience with cross-ideological negotiations, and pragmatic approach to politics maintained by the leadership of the major Islamist party, Ennahda (Bellin, 2013; Stepan and Linz, 2013; McCarthy, 2019). However, just a few months before the constitution’s adoption, when non-Islamist parties withdrew from the NCA and called for its dissolution, few would have predicted such a broad approval. Drawing on more than 50 in-depth interviews with partisans, members of civil society and experts, analysis of the constitution’s consecutive draft, opinion polls, and secondary literature, this article disentangles the constitutional agreement. It focuses on three key areas of divergence between the political parties, and the resolution of the contentious issues between the outset of constitution-making and the constitution’s adoption. These are the religion-state relations, the configuration of the political system, and the resignation of the Ennahda-led government coalition. I show that despite their initial electoral weakness and their fragmentation compared to Ennahda, non-Islamists managed to turn the constitution increasingly to their liking, while also restricting Ennahda’s control over the government. Although multiple factors contributed to arriving at a constitution that was acceptable across the religious divide and consequently agreed, this article highlights the importance of a situation in which there was no alternative to settling the differences, a state of affairs that was facilitated by the changes in the balance of power between Ennahda and its non-Islamist political rivals between 2011 and 2014. This finding brings nuance to the debate about the political transformation in Tunisia. It also contributes to the literature on democratization which has predominantly focused on the regime-opposition power configuration (e.g. Stradiotto and Guo, 2010), by stressing the importance of the power balance between the opposition forces themselves.