Research and theory suggests that children and families are best served by a preschool to third grade approach (PreK−3) to early childhood education that is aligned, integrated, and based on developmentally appropriate practice. Because of the recent expansion of publicly funded preschool programs, principals are becoming increasingly responsible for overseeing these programs, and, as instructional leaders, play a critical role in establishing working conditions and creating organizational capacity to support teachers’ professional growth. Unfortunately, however, early childhood education is rarely addressed in principal preparation programs and principals are often unfamiliar with the science of child development. Using a qualitative case study design, the current study describes how one school principal began to lead a PreK−3 community at her school by examining data collected across a two-year period as the principal led a professional learning community with preschool, transitional kindergarten, and kindergarten teachers. The PreK−3 Learning Communities Competencies for Effective Principals developed by the National Association of Elementary School Principals were used to identify the thoughts, behaviors, and actions of one principal as she engaged in this work. Results from this study further discourse in the field as to what this approach looks like in practice and call attention to the need for structural changes in preschool and elementary settings. (author abstract)