This study documented variations in program designs and implementation strategies, linking them to beginning teachers' professional growth, particularly reflective practices. Data were collected in six sites during 1999-00 as part of an evaluation of the implementation of the California Formative Assessment and Support System for Teachers, which is part of the Beginning Teacher Support and Assessment (BTSA). BTSA program directors were interviewed, and beginning teachers and support providers participated in focus groups. Data analysis illustrated both the importance and the limitation of program structures in contributing to program outcomes. Having the "pieces" in place was a necessary condition for implementation but not sufficient to achieve the desired accomplishment of reflective practice. Equally important was the web of understanding, interpretation, and meaning surrounding the participants. Participants themselves both shaped and were shaped by the interpretive perspectives encompassing their work. Program directors who were aware of the larger context and paid attention to shaping that context were able to influence the position of their programs. Ultimately, the opportunities for beginning teachers to develop their reflective practice was tied to their experiences with the particular support providers with whom they had been matched. The quality of this relationship was key to program success. (Contains 21 references.) (SM)