The effectiveness of outside experts in professional development in Jewish schools has been questioned in light of scholarly critique of this approach. This case study examines the sociocultural context of one such long-term project aimed at school improvement through early childhood (EC) curriculum development. The research identifies cultural and organizational factors contributing to the effectiveness of the outside expert's 7-year involvement in the project. Qualitative methods include teacher and administrator interviews, artifacts, and field notes. Findings stress the importance of shared values, collaborative learning, teacher autonomy, and supportive school leadership for success of this professional development model.