This study proposes a network approach to interorganizational cooperation in peace operations. It suggests that in addition to key organisational characteristics that are already established in the literature, such as organisational type, the nature of relationships among intergovernmental organisations (IGOs) drives the formation and evolution of inter-IGO networks in peace operations. To evaluate my hypotheses, I use the temporal exponential random graph model (TERGM). The empirical analysis provides evidence that the formation of interorganizational networks among IGOs in peace operations is largely driven by relational effects, e.g. network effects.