This report, the third in a series of reports from the longitudinal evaluation of the Eisenhower Professional Development Program, examines the effects of professional development on improving classroom teaching practice. The Eisenhower Professional Development Program, Title II of the Elementary and Secondary Education Act, is the federal government's largest investment that focuses solely on developing the classroom teachers' knowledge and skills. Drawing on longitudinal data from approximately 300 teachers, this report discusses the impact of the types of professional development activities supported by the Eisenhower Professional Development Program. Results indicate that professional development focused on specific, higher order teaching strategies increased teachers' uses of these strategies in the classroom. This effect was even stronger when the professional development activity was a reform type, rather than traditional. Teachers in the sample did not consistently receive high quality professional development, and teachers in the same school tended to have quite different professional development experiences. There was little change in overall teaching practice from 1996-99. Despite little average change over time in teaching practice, individual teachers varied in their classroom practices, and moderate variation occurred in the classroom practices of individual teachers from year to year. (SM)