The professional development school is an effort to invent an institutional coalition that will bring together universities, schools of education, and public schools. This report urges the creation of a relatively small number of schools as professional development schools (PDS), designed to be the focus of professional preparation, school research, and the improvement of teaching. Six principles are offered on how PDS should organize themselves: (1) teaching and learning for understanding; (2) creating a learning community; (3) teaching and learning for understanding for all children; (4) continuing learning by teachers, teacher educators, and administrators; (5) thoughtful long-term inquiry into teaching and learning; and (6) inventing a new institution. The rationale for creating a network of PDS and the relationship of these schools to educational reform are discussed. The report concludes by suggesting what Holmes Group universities should do to make a start in establishing PDS. (IAH)