In 2014, Tunisia’s National Constituent Assembly (NCA) almost unanimously approved the country’s first democratic constitution despite significant identity-based divisions. Drawing on the Tunisian case, the article explores the role of an inclusive constitution-making process in fostering constitutional agreement during democratization. Emerging studies that link different process modalities to democracy have so far brought only limited illumination to how inclusive processes matter, nor were these propositions systematically tested. Using process tracing, and building on original interviews gathered in Tunisia between 2014 and 2020, this article traces a causal mechanism whereby an inclusive constitution-making process allowed for a transformation of interpersonal relationships between political rivals. It demonstrates that more than two years of regular interactions allowed NCA deputies to shatter some of the prejudices that initially separated especially Islamist and non-Islamist partisans and develop cross-partisan ties, thus facilitating constitutional negotiations. However, I argue that the way these transformations contributed to constitutional settlement is more subtle than existing theories envisaged, and suggest alternative explanations. The article contributes to the debate about constitution-making processes by unpacking the understudied concept of partisan inclusion and applying it empirically to trace its effects on constitutional agreement, bringing precision and nuance to current assumptions about its benefits.