This study was conducted to examine the effectiveness of Prevent-Teach-Reinforce for Young Children (PTR-YC) using a single-case experimental design. PTR-YC is a manualized intervention designed to address challenging behaviors for children in preschool and childcare settings using the framework of positive behavior support. Participants included three preschool-aged children who were receiving special education services in public preschool classrooms. As hypothesized, the use of PTR-YC resulted in two primary effects, including a decrease in challenging behaviors and an increase in desirable behaviors across all three cases. Secondary data revealed favorable increases in prosocial (or positive) interactions between teacher and child for all three cases. PTR-YC interventions were also associated with high rates of perceived social validity. Implications for the use of PTR-YC in preschool settings are discussed along with considerations for the importance of coaching to increase fidelity and the effect on teacher--child interactions.