Cooperative forms of policy implementation bear the promise of being an answer to the policy delivery challenge resulting from policy growth, with the quality of network management often rated as a key success factor. The positive relationship between network management and performance in networks, however, is primarily supported by theoretical reasoning rather than empirical evidence. The present study empirically investigates this relationship in the context of rapid policy growth resulting from a change in the governance structure in the field of smoking prevention in Switzerland. The results of the analyzed 13 Swiss smoking prevention networks and the 187 associated projects show that network management improves the performance of new policy projects by facilitating access to implementing partners and target groups, but has no impact on output delivery in existing interventions. The study shows that networks, if actively managed, can be a means to ensure adequate enforcement in the context of increasing numbers of new policies.