This study examines the impact of a new master's degree program on the instructional practices of K-8 in-service teachers. This 2.5-year master's program was designed to deepen in-service teachers' knowledge in science and mathematics and promote greater use of reform-oriented instruction. Teachers' instructional practices were captured annually through classroom observations, student reports, and teacher self-reports. Based on the results of the first 2 years of program implementation, there was a significantly positive change in the extent to which teachers implemented reform-oriented practices in the classroom. However, these changes were most prominent in the first year of the program. A comparison of different data sources indicated that teachers perceived their progress toward reform-oriented instruction as far more steady than indicated by outside observers or student reports. Implications for current policies, professional development, and further research are discussed.