During the last 30 years, growing demand for science-based policy making has contributed to the mobilization of scientific cooperation alongside transnational political arrangements for addressing environmental issues. Following the contemporary trend towards regionalizing environmental policy and practice, many of these scientific joint efforts have focused on a regional scale. This article examines regional scientific cooperation in the context of the institutionalization of mountain regions in Europe. Such cooperation can be observed from the Pyrenees to Central Asia, albeit with a degree of variation that largely remains unexplored in scientific research. Sometimes scientific cooperation served to lay the groundwork of a mountain policy initiative, other times it appeared in its wake; some examples appear as loose networks of individual scientists, others are set up as formalized monitoring and observation centers; finally, some scientific joint efforts are formally linked to, or incorporated in a mountain policy initiative, while others are largely independent. The article proposes a new typology for understanding the interactions between regional scientific mobilization and regional policy making and provides up-to-date portraits of six main cases.