While there has indeed been scholarly interest in constitution-making, in particular in the context of democratization, there has been little empirical analysis of how it unfolds in situ. Legal scholars have tended to consider that the provision of expertise in constitution-making is marginal, and hence not worthy of in-depth examination. The literature on constitution-making interested in the transnational dimension is driven by normative concerns rather than descriptive ones. This chapter aims to contribute to filling this gap. This chapter argues that studying the transnational dimension of constitution-making is an important element of understanding how political systems are built. Drawing on discussions on the political dimension of expertise in legal reforms, the chapter describes how this translates to constitution-making, providing a more accurate and comprehensive picture of the transnational dimension of constitution-making, with an empirically driven account of foreign expert involvement. This chapter uses the case study of the 2014 Tunisian constitution to shed light on the transnational dimension of constitution-making.