Switzerland is known for its euroscepticism and its unique bilateral relationship with the EU. While Swiss differentiated integration (DI) has already been the subject of studies (Jenni, 2016), less has been said on the informal institutional integration of Switzerland (Lavenex and Schwok, 2015). The aim of this paper is to provide a comprehensive account of Swiss membership in European Administrative Networks (EANs). We evaluate whether membership follows the functional, informal pattern characteristic of EANs, or is also influenced by intergovernmental, EU foreign policy prerogatives. We conduct an exploratory study of different drivers, relying both on descriptive analysis and bivariate logistic regressions. Our main source of data is the novel dataset DITE III (Lavenex, Nanchen, Guaschino and Poussardin, forthcoming). Our findings indicate that Swiss functional integration in EANs is more affected by foreign policy drivers than expected.