This essay posits a problem of "fit" between five streams of reform (subject matter teaching, diverse student populations, uses of student assessment, social organization of schooling, and professionalization of teaching), and prevailing configurations of teachers' professional development. It argues that the dominant "training" model of teachers' professional development, a model focused primarily on expanding an individual's repertoire of well-defined classroom skills, is not adequate to the ambitious visions of teaching and schooling embedded in present reform initiatives. The paper begins by posing ways in which current reform movements shape challenges, possibilities, and constraints for teachers' professional development. Section 2 frames a policy dilemma that revolves around the limitations of the dominant training paradigm. A third section introduces principles that seem especially congruent with reform requirements, together with examples of four options that appear to hold promise: (1) teacher collaboratives and other networks; (2) subject matter associations; (3) collaborations targeted at school reform; and (4) special institutes and centers. The final section outlines emerging issues that bear on the fit between reform imperatives and teachers' professional development such as the complexity and uneven pace of systemic reform, problems of "fit," and the school work place and teachers' opportunity to learn. (Contains approximately 75 references.) (Author/LL)