Teachers play a key role in the quality of education provided to students. The Maine Center for Research in STEM Education (RiSE Center) at the University of Maine has worked with partners to design, implement, and evaluate several programs in the past eight years to provide professional learning opportunities and support for Maine's STEM teachers, leading to significant impacts for teachers and students across the state. A strategic investment in developing teacher leadership capacity played a key role in expanding the initial partnership to include teachers and school districts across the state. With support from education researchers and staff at the RiSE Center, STEM teachers have taken on roles as leaders of professional learning opportunities for peers and as decision makers in a statewide professional community for improving STEM education. This article describes the structures that have fostered teacher leadership and how those structures emerged through partnership and collaboration, the ways in which teacher leadership has amplified the resources we have been able to provide to STEM teachers across the state, and the outcomes for Maine students.