There is a significant gap in academic achievement between rural and urban students in China. Policymakers have sought to close this gap by improving the quality of teaching in rural areas through teacher professional development (PD) programs. Despite billions of dollars in investment, however, there is limited evidence on the effectiveness of such programs. In this paper, we evaluate the impact of a PD program-National Teacher Training Program (NTTP) on the academic achievement of students in rural China. We further examine the causal chain through which the program does or does not impact student achievement. By analyzing data on 84 teachers and 3,066 students from one Western province, we find that at a minimum, the NTTP has no effect on math achievement. In fact, it may even harm student academic achievement. We also find that while the program has a positive effect on math teaching knowledge of teachers, it has no significant effect on teaching practices in the classroom. Taken together, these results indicate that teachers may have improved their knowledge for teaching from NTTP, but did not apply what they learned to improve teaching practices or student learning.