Starting Smart and Strong is the David and Lucile Packard Foundation’s kindergarten readiness strategy to build, test, and scale up community-driven solutions in early learning. The Foundation is supporting three California communities—East San Jose, Fresno, and Oakland—in a ten-year effort to bring together public and private partners to determine and test approaches that address inequities in quality early childhood experiences, professional development for early educators, and kindergarten readiness. Having completed its sixth year in 2020, Starting Smart and Strong aims to develop best practices that can be useful in any community. Engage R+D is working with the Foundation on an evaluation to understand how Starting Smart and Strong communities are developing early learning support systems and to identify best practices for implementation and taking solutions to scale. This 2021 evaluation report focuses on a period of expansion and learning as the three communities worked to scale and spread innovative and effective professional development practices. (author abstract)