Elementary teachers were involved in a two-year grant focused on professional development using lesson study processes to increase their understanding of mathematics content and effective mathematics pedagogy. The primary research questions focused on how 16 elementary teachers described their professional growth after being involved in lesson study in a professional learning community with other teachers and university professors and how they described the impact the program had on their teaching of mathematics. Case study methodology provided the tools for researchers to study complex phenomena within a professional learning community setting. Collected data included interviews of selected teachers focused on the lesson study process, teacher journal reflections, and recordings of individual teacher discussions of video taped segments of their teaching. Data indicated the participants valued collaboration within the community of learners and a change in practice through a focus on student discourse, student thinking, and questioning strategies. The majority of teachers demonstrated the change in practice; however, not all teachers demonstrated such growth.