An innovative approach to the preparation of school administrators is described in which instructor and student come together in a learning situation that integrates three core components: (1) formative portfolio assessment; (2) reflective practice; and (3) cognitive apprenticeship. The operation and impact of this approach are illustrated through its implementation in a graduate administrator preparation program at Oakland University in Rochester (Michigan) involving 17 students in 3 cohort teams. Qualitative ethnographic research methods were used to document the experiences of these graduate students in the cognitive coaching process, with a focus on the contents of their formative professional development portfolios and their accompanying reflective papers. Analysis of the data revealed deepening understanding, creation of meaning, and integration of metacognitive analysis, as well as enhanced linkage of theory and practice. Students became more open to exploration of complex problems of practice and reaffirmed themselves as developing leaders. Appendixes contain sample portfolio documentation and a list of proficiencies of the effective principal. (Contains 15 references.) (SLD)