In recent decades, European neighbouring regions have gained importance in the processes of spatial integration within the European Union. Based on the European Cohesion goals, cross-border cooperation among institutions supports the socio-economic development of the regions and enhances equality across Europe. In order to study cross-border institutional cooperation, this chapter develops a conceptual model of cross-border institutional thickness (CBIT) and tests its applicability on the case study of the Rhine-Waal region (NL-GE). It is explorative research, based on the Interreg IVA project database. The chapter focuses on institutions, cross-border initiatives and policies, and contributes to the body of empirical evidence on the issue. A set of social network analysis techniques are applied to measure the CBIT model and unfold some facts about cross-border interactions among institutions by means of Interreg projects in the Rhine-Waal region.