hours students must complete in mathematics, science, and technology for elementary, middle school, and high school licensure, as well as for recertification. Middle or high school certification criteria may also include assessment of teachers’ subject-matter knowledge. In some states, teachers may move through a number of levels of certification over the course of their careers. For example, teachers may receive “initial” certification upon entry into the profession, followed by a “professional” certificate after several years of refining their teaching skills and demonstrating proficiency in the classroom. The nonprofit National Board for Professional Teaching Standards (NBPTS) offers a relatively new form of certification (e.g., NBPTS, 2000a, 2000b), which allows experienced teachers to demonstrate and gain recognition for accomplished practice independent of any particular state’s definitions of proficiency.

Interest in improving teaching quality has become more prominent at both state and national levels. Part of this attention is focused on teacher content knowledge, where there is concern, for example, that 30 percent of U.S. high school mathematics teachers overall, and a higher proportion of teachers in high-poverty schools, do not have a major or minor in their field (National Center for Educational Statistics [NCES] 1995, 1997b; Ingersoll, 1998).

Professional learning opportunities present themselves to teachers in many ways and contexts (McLaughlin, 1993), forming what has been characterized by some as “a patchwork” rather than a coherent program of continuing education (Wilson and Berne, 1999, p. 174). Studies of professional development reveal discrepancies between what is known or believed about facilitating meaningful learning and what most mathematics, science, and technology teachers actually experience in these programs. Typically, teachers attend one-time events that deal with topics unrelated to any school priorities or issues regarding their teaching practice, and that