This article addresses the impact of intensive, job-embedded mentor-coaching for 36 teachers and teaching assistants in relation to their language and literacy proficiency and the fidelity of their implementation of the Opening the World of Learning curriculum. The literacy scores for the majority of teachers in both the treatment and comparison conditions in the Early Childhood Educator Professional Development Promoting Education for Adults and Children Partnership Project, as measured by the Nelson-Denny Reading Test, were very low. Moderately high levels of implementation fidelity, on average, were achieved by the treatment teachers as they learned to use a literacy-rich curriculum. After 3 years of training and coaching, treatment teachers showed higher scores on the Teacher Behavior Rating Scale measure of language and literacy-related teaching behaviors than the comparison teachers, and these differences were large when examined as effect sizes. (Contains 4 tables.)