Cooperation and networking among a variety of organisations for the purpose of research, projects, and other activities ranges from ad hoc to long term organisational relationships, formalised or based on informal cooperation. Although informality is frequently much valued and drives organisations to partner on substance rather than bureaucracy, formalisation of networks and cooperation might be indispensible for effective partnerships and activities, as well as representation of mutual interests beyond the national level. How shall such networks be formalised at European and/or national levels so that they are flexible enough, involve minimum bureaucracy, and engage the maximum scope of possible activities? This article focuses on the analysis of possible legal structures facilitating the work of a group of entities and individuals engaged in cross-border activities. This study examines the potential of national legal opportunities in five countries: Belgium, Estonia, Lithuania, Poland and the Netherlands, and the proven legal form of EEIG in reducing the barriers for cooperation, as well as the advantages and disadvantages of these legal forms for a formalized network and the purposes it serves.