This study examined the mathematical discourse of elementary school teachers and their students while participating in a year-long professional development project focused on implementing reform-based mathematics curriculum. The teacher participants included 12 teachers, two from each grade level from Kindergarten through Grade 5. Field notes were collected during observations and were analyzed as raw qualitative data. Inductive qualitative analyses of classroom observation data indicated that the level of enacted mathematical tasks and teachers' questioning strategies influenced the types of mathematical communication in classrooms. Quantitative analyses of data regarding teachers' level of questioning and implementation of mathematical tasks found an increase in high-level questions and tasks, but the increase was not statistically significant. Implications for the design of professional development and further research in this area are shared.