Lesson Study is an internationally recognised professional development approach for teachers. This case study explores the impact of implementing Lesson Study in the early grades of a South African primary school, pertinently targeting early childhood mathematics teachers. The evidence suggests that Lesson Study has the potential to positively influence content knowledge, pedagogical content knowledge, general professional development and creative teaching of early grade teachers. The study established that Lesson Study enhanced intergrade cooperation and curriculum development and flow. Participants regarded the collaborative experience as deeply enriching and fulfilling. Although some implementation challenges were encountered, these were not insurmountable and the overall benefits of Lesson Study outweighed the potential obstacles.