This is the summative evaluation for the My Sky Tonight: Early Childhood Pathways to Astronomy is a National Science Foundation funded Full-Scale Development project that was designed to support informal science education practitioner’s ability to provide astronomy learning for young children ages 3-5 years. Based on prior research and assessment of the field, the project team identified that many informal educators lack the astronomy content, interpretive strategies, and confidence they need to effectively engage audiences of families with preschool-aged children. Three mechanisms were