Drawing on their research and professional development with teacher leaders in Maine, the author sees reasons for optimism in many examples of teachers, schools and districts that are supporting and building teacher leadership capacity. Yet, the author also highlights conditions that constrain the development of teacher leadership. The state’s limited fiscal resources have produced repeated budget cuts over the past decade, reducing the number of teachers and supports to meet the challenges of accountability demands. Geographic isolation and the small size of many schools in Maine are also factors that reduce opportunities for learning new ideas and accessing professional development. Entrenched perceptions among both administrators and teachers that reflect more traditional notions of teacher leadership persist in many schools and often limit teacher leadership to a few, formal roles with limited authority and impact. Teachers often don’t recognize their work as leadership, or shy away because of persistent norms of egalitarianism. The author argues that making the promise of teacher leadership a reality will require more coordinated effort at all levels, including policy change, increased resources, and support within and outside school systems. A more profound transformation must occur in practitioners’ conceptions of their own and others’ leadership.