The job of principals is demanding and evolving; consequently, they cannot lead alone. Teacher leaders can be a valuable resource if principals know how to build leadership capacity in teachers and practice distributive leadership. Understanding principals' and teachers' perceptions of their needs and how to best meet these needs can aid principals in building, and sustaining teacher leadership capacity. Therefore, the purpose of this qualitative study was to identify principals' and teachers' perceptions of their need and efforts to build teacher leadership capacity through school-level supports and professional development as well as principals' and teachers' perceptions of their ability to act as teacher leaders having participated in school-level professional development. Existing literature on building teacher leadership and sharing leadership responsibilities as it relates to the role of the principal, professional development, and sustainability was reviewed. Qualitative data were collected from 18 teachers and six principals in teacher focus groups and individual principal interviews in six high schools in one division in southeastern Virginia. At the conclusion of the data collection process, the researcher examined the perceptions of the teachers and the principals. The analysis revealed principals' and teachers' perceptions about the following areas: formal and informal leadership roles; professional development opportunities, teacher leadership structures in schools, strategic plans for building teacher leadership, mentor relationships between principals and teachers, barriers to teacher leadership, and recommendations for improved professional development opportunities. The study reinforced the notion that school-level supports and professional development need to be systematic and strategic.