This study interviewed 45 ninth-grade teachers in 4 secondary schools in Ontario, Canada, in the spring of 1997 regarding their perceptions of their professional learning needs. Respondents were part of a 3-year research and development study, "Change Frames." Analysis is based on the view that the most meaningful teacher professional development takes place not in a workshop or in discrete, bounded conversations, but in the context of professional communities, discourse communities, and learning communities. Teachers typically belong to multiple professional communities, each of which functions somewhat differently as a strategic site for professional growth. Thus, it is argued, professional growth is, at root, about enabling professional community. Both case studies and a cross-case analysis were carried out. Findings indicate that teachers valued professional development that was directly relevant to their practice. However, many teachers tended to look to experts outside their workplace to fill this need, often with disappointing results. Findings suggest that the transmission model of professional development is often incongruent with adult learning principles and antithetical to building the conditions of shared purpose, infrastructure, and domains for action that enable schools to become effective learning organizations. (Contains 101 references.) (Author/SM)