Because of the devolution of tasks and powers from the national political level to subnational levels, subnational governments such as municipalities and provinces are increasingly compelled to express their interests in the national and European arenas. However, to achieve substantial weight, authority, receptiveness, and success in both arenas, active cooperation with other subnational authorities is needed. The question is to what extent subnational authorities acknowledge this need for cooperation and how this cooperation is being organized and structured. More specifically, in this study, the function and role of collective public affairs (PA) activities are investigated. Qualitative interviews with 17 PA professionals and 24 PA practitioners, experienced in working for subnational authorities, were held to find out how subnational governments in the Netherlands together organize PA in both arenas. The results show that subnational cooperation is of ultimate importance for creating a favorable position in these arenas. Such cooperation is favorable if subnational authorities together constitute a clear profile and render thematic collaboration in which the citizen is seen as the most important stakeholder. Further, the level of knowledge concerning the national and European arenas should be optimal among all parties involved in which the PA professional serves as a liaison officer who connects the various stakeholders.