Athough positive behavior support (PBS) has been established as an effective approach for resolving the challenging behaviors of many populations, little research has evaluated PBS with children under the age of 4 years. In addition, few studies have considered the effectiveness of PBS delivered via consultation in typical childcare and preschool settings. This study was conducted to examine the effects of PBS implemented by typical classroom staff for two 3-year-old girls in a community-based preschool accredited by the National Association for the Education of Young Children. Within the context of A-B-A-B designs, the data indicated reductions in challenging behaviors and increases in engagement for both girls in two separate group contexts. Fidelity data indicated that some components of the PBS plans were implemented but others were not. The findings support the efficacy of PBS with young children in natural settings while raising questions for future research regarding the utilization and efficiency of PBS support plans.