The purpose of this article is to describe the professional development (PD) model for preschool literacy and language instruction that took place in a 3-year, 2-tiered Early Reading First project in 9 Head Start and community-based school classrooms. In our tiered model, the Tier 1 level was classroom instruction and Tier 2 was intervention instruction. Through our data-driven PD model, we sought to systematically provide workshops for all classroom teaching staff based on the evidence-based literacy/language skills and learning strategies. Teachers received approximately 55 hr a year in training. Classroom coaches each worked in 3 classrooms and spent approximately 4 hr a week per classroom working to plan with teachers and supporting instruction. Children were regularly assessed in areas of literacy/oral language and teachers were assessed on the quality of the classroom environment and teacher fidelity of implementation of strategies learned during coaching and workshop training. Teachers also provided feedback on the quality of workshop training and participated in self-reflection discussions about implementation. Each of these data sources was used to modify training and coaching. The article provides further information about training, coaching, and data sources as well as teacher and child data that support the use of the model. (Contains 2 tables and 4 figures.)