Early childhood education (ECE) can have a profound effect on improving the lives of young children. However, too many children attend ECE programs that are mediocre at best. Increasingly, federal, state, and local policy makers have focused on developing and implementing professional development systems to prepare, train, and improve the early childhood workforce as a means of improving ECE quality. This entry examines the ways that a conceptual framework guides the structure and content of teacher preparation programs in order to help improve teachers’ practices and student learning.