This paper presents the voices of California beginning teachers who completed focus group discussions on their perceptions of their own development as reflective practitioners, analyzing the nature and extent of teachers' thinking. Teachers were part of the California Formative Assessment and Support System for Teachers (CFASST), which is framed around a cycle of reflective inquiry and uses the California Standards for the Teaching Profession as the standard description of reflective practice. Analysis of the focus group data indicated that beginning teachers in the CFASST program reflected regularly about their practice, and they used multiple formats (e.g., written, verbal, small groups, one-to-one, and alone) to enhance reflection. While many described themselves as being naturally reflective about their work, data indicate that the nature and extent of such thinking changed as they participated in a program of structured support organized around cycles of inquiry and reflection. Reflection became more focused on specific elements of curriculum, pedagogy, and assessment. At the same time, teachers began to examine larger issues related to the profession and to the organization of schools. (Contains 14 references.) (SM)