Despite abundant research on street-level bureaucrats (SLBs), our knowledge of the role of leadership for SLBs’ policy implementation remains limited. Drawing on theories of implementation, distributed leadership (DL) and social change (involving self-efficacy), we argue that DL practices hold promise for fostering implementation of policy reforms at the frontlines. Specifically, we focus on the DL practice of SLBs performing leadership functions of professional support and development collectively in teams. Our study is based on fixed-effect analyses of 5 year panel surveys of more than 2,000 teachers from about 200 schools in the context of a complex reform Danish public school reform, which was strongly opposed by professional teachers. We find that teachers’ participation in DL teams directly and substantially enhances their implementation of the reform in their teaching. Such participation also has an indirect small, significant implementation impact mediated by fostering a stronger perceived self-efficacy especially in the beginning of the reform. The positive implementation impact of SLB's participation in DL teams is remarkable and may provide a critical test given the strong professional opposition to the reform.