Migration is often perceived as a challenge to the welfare state. To manage this challenge, advanced welfare states have established transgovernmental networks. This article examines how domestic factors condition the interaction of representatives of advanced welfare states when they cooperate on transnational welfare governance. Based on new survey data, it compares who interacts with whom in one of the oldest transgovernmental networks of the European Union (EU) - the network that deals with EU citizens' rights to cross-border welfare. First, the authors perform a welfare cluster analysis of EU-28 and test whether institutional similarity explains these interactions. Furthermore, they test whether the level and kind of migration explains interaction and examine the explanatory value of administrative capacity. To test what drives interactions, the study employs social network analysis and exponential random graph models. It finds that cooperation in networked welfare governance tends to be homophilous, and that political cleavages between sending and receiving member states are mirrored in network interactions. Domestic factors are key drivers when advanced welfare states interact.