In this article, the author discusses some of the most serious challenges--intellectual, institutional, and political--that he sees for the future of professional learning in education. He states that one common solution to these challenges would be for educators to begin to act more like professionals. One thing is clear about the early stages of systemic school improvement efforts--a body of expert knowledge is required to carry them off. The knowledge is partly technical, partly managerial, and partly social/political. It is time to make this knowledge proprietary--that is, to require that practitioners master it before they advance to positions of formal authority and responsibility, and to use the knowledge, as professionals do, to exclude from practice people who do not have it. Another prerequisite of professionalism is to begin to treat knowledge of the profession as collective rather than individual. The work of school improvement is unlikely to advance much beyond its current level unless educators begin to exercise some professional accountability for practice within their own ranks and unless they begin to consolidate their authority and influence to hold policy makers accountable for the investments in the institutions and professional development necessary to make large-scale improvement work.