We evaluated an Early Childhood Educator Professional Development (ECEPD) project that provided high-quality, sustained, and intensive professional development designed to support developmentally appropriate instruction for preschool-age children based on the best available research on early childhood pedagogy, child development, and preschool learning. Participating teachers in ECEPD classrooms received extensive, intensive, and continuous professional development and coaching on critical features of evidence-based early literacy practices essential to school success. Evidence from comparisons of classroom instructional variables indicated consistent differences for teachers participating in project-directed professional development compared with their peers who did not participate in similar programs. Anticipated benefits of participating in high-quality, sustained, and intensive professional development designed to support developmentally appropriate instruction for preschool-age children based on the best available research on early childhood pedagogy, child development, and preschool learning were documented. (Contains 2 tables and 1 figure.)