This report presents the details of a year-long study conducted by Research for Action of the impact and implementation of the Children's Literacy Initiative (CLI) Pre-K Intervention. Thirty-five district-operated and community-based Pre-K programs from Broward County Public Schools and the Early Learning Coalition of Broward County were enrolled and randomly assigned to programs with the intervention and those operating under "business as usual" conditions. CLI hypothesized that state and local decisionmakers need a comprehensive Pre-K curriculum based in equal parts on the science of child development and the realities of the current early childhood workforce. CLI's intervention targeted low- and middle-income children enrolled in state-funded universal public Pre-K settings, investing in resources for children and the programs that serve them who live in historically under-resourced communities. The evaluation was guided by three overarching aims: (1) Examine the impact of CLI's intervention on key skills that prepare children for success in Kindergarten ("Impact Study"); (2) Describe thresholds for fidelity of the intervention and document the extent to which CLI met the thresholds in the study ("Implementation Study"); and (3) Evaluate the implementation of CLI's intervention in classrooms serving students with disabilities or development delays ("Case Study"). RFA found that implementing CLI's program was challenging, especially when it came to providing enough training for teachers and site leader professional learning. Because of these challenges, the study didn't find any evidence that CLI's program made a difference in how well students understood phonological awareness or numeracy (sounds or numbers). Overall, kids in both groups ended the year with skills that were expected for their age.