Thermalism is a key socio-economic activity for the Galicia–North Portugal Euro-region. It also acts as a pillar to support other activities, is a net contributor to employment and regional wealth, and provides an opportunity for growth that has yet to be maximized. It is a heavily regulated activity at various stages of its production process, guided by multiple entities (in health, tourism and geology spheres) whose competencies often overlap. Moreover, it is subordinate to a variety of technical and administrative procedures, making it an activity that requires excessively demanding administrative processes. This is true not only for the process of opening thermalism establishments and attracting initial investment, but also in daily operational routines. This paper presents a review of the legal framework for thermal activity across the Euro-region, highlighting legal differences between Spain and Portugal. Furthermore, this chapter shows how the legal framework is responsible for creating conditions that foster different levels of sector development. In doing so, this legal framework affects competition and hampers communication between institutions and consumers. The major consequence of this is to hinder internationalization of thermalism. The authors demonstrate the importance of strategically aligning existing thermal laws across the Euro-region to promote sustainable industry growth; a key concern given the industry’s reliance on natural resources (hot springs and natural mineral water). Furthermore, by doing so, policymakers could help foster a more favourable environment for developing and reinforcing thermalism in Galicia–North Portugal.