Impact of in-service professional development programs for early childhood teachers on quality ratings and child outcomes

High pedagogical quality in early childhood education and care (ECEC) is related to developmental outcomes in young children. This review summarizes findings from (quasi)-experimental studies that evaluated in-service training effects for ECEC professionals on external quality ratings and child development. The aggregation of findings at teacher level (including 36 studies with 2,891 teachers) revealed a medium in-service training effect on process quality (effect size [ES] = 0.68, SE = 0.07, p < .001). Furthermore, a subset of nine studies (including 486 teachers and 4,504 children) that provided data on both quality ratings and child development were analysed, and they showed a small effect at child level (ES = 0.14; SE = 0.02, p < .001) and a medium effect at the corresponding classroom level (ES = 0.45, SE = 0.11, p < .001). Variance in effect sizes at child level was significantly related to in-service effects on quality ratings (53% explained variance). The results show that quality improvement is a key mechanism to accelerate the development of young children.