Engaging teachers of young children in effective in-service professional development is a critical component of establishing high quality early childhood education. However, not all professional development offerings are effective in imparting new knowledge, enhancing teacher practice, or improving child outcomes, making it difficult for teachers and directors to select professional development that will benefit their centers. This paper critically reviews the research literature on professional development for early childhood education to identify what features of professional development make a difference for teacher interactions and children's learning and development. Guidance is provided for selecting professional development opportunities which meet the needs of children and teachers. Recommendations for how to create an ongoing professional development program within an early childhood center by creating a professional learning community are also made. Such an approach supports the center to become a place that values learning and continued education for all professionals.