In understanding what drives the development of network administrative organizations (NAOs) in mandated networks, power bargaining is central. The authors execute a comparative longitudinal case study of NAOs in two policy-mandated networks. The article focuses specifically on the role of power in these developments and concludes that differences in NAO development arise from power dependencies, which are attributable in part to sector characteristics. It is proposed that mandated network members’ greater interdependence and greater dependence on external nonmembers, as well as whole network dependence on external actors, partly determine mandated networks’ NAO design. These networks will have larger and more capable NAOs (with more staff), accept sharing control of the NAO executive with the mandating party, and have broader responsibilities.