To what extent can a large-scale national teacher-enhancement project help science teachers employ new pedagogical methods in the science classroom? In this study, data from 13 high school physics teachers who taught 23 classes with 401 students were examined to determine the extent to which a teacher-enhancement project can alter teachers' pedagogy. Three groups of teachers were examined: experienced users of the new pedagogy, beginning users of the new pedagogy, and a group of comparison teachers who used traditional instructional methods. Results suggest the reform effort can increase the extent to which teachers engage students in experiments and use alternative assessment methods; however, helping teachers use constructivist discussion methods and discuss the nature of scientific inquiry appears to be more difficult. The implications for inservice teacher education are discussed.