The use of teacher leadership in PK-12 education has experienced a resurgence since the late 1990s as school leadership models have evolved to include the engagement of diverse stakeholders in school and district leadership processes aimed at improvement efforts. Despite this resurgence, there remain several barriers to understanding the nature of the work in which teacher leaders engage and the contributions that they make. This grounded theory study examined teacher perceptions of teacher leadership, the types of work in which teacher leaders do and should engage, the boundaries of that work, and barriers to teacher leadership. Leveraging interviews with teachers in a large urban school district, we found that teachers function in many domains of work and are eager for pathways to leverage their expertise, but some faced a lack of access to their school's leadership and management space. We conclude by discussing the implications from our findings for school- and district-level leaders, local and state policymakers, and educational leadership preparation programs.