Whole-child curricula seek to promote learning by encouraging children to interact independently with the equipment, materials, and other children in the classroom environment. A recent meta-analysis showed that, on average, children exposed to whole-child curricula do not out-perform children in classrooms where curricula are developed locally by teachers or preschool programs (Nguyen, 2017). It may be because implementing a whole-child curriculum can be challenging, and programs often must train and mentor teachers to implement the chosen curriculum faithfully. We also cannot expect that each teacher will implement a curriculum identically across classrooms given that children come into the classroom with their own diverse needs. The current study seeks to document variations in the curriculum implementation of High Scope, the curriculum used from the famous Perry Preschool Study, by observing classrooms in which the same curriculum and training are provided to teachers. Such a study offers an opportunity to examine how a curriculum looks in practice in efforts to better prepare low-income, ethnically and linguistically diverse children for school and can help address what particular challenges teachers may face in implementing a curriculum with fidelity.