Research Findings: This study examined the associations between early childhood education (ECE) teachers' pre-service education (PE), professional development (PD) experiences, ECE quality, and child development. The participants included 52 teachers and 706 children from 52 preschool classes in Shanghai and Guizhou. Teacher educational level was associated with classroom interaction quality. The frequency and diversity of PD activities that ECE teachers experienced in the past year were also related to overall ECE quality. Mediational analyses indicated that the diversity and frequency of PD were indirectly associated with child development through ECE quality. Region of residence moderated the associations between PE and child development and between ECE quality and child development. Practice or Policy: Together, the findings highlight the need for policy to support ECE teachers' professional learning from pre-service education to ongoing professional development.