This study examined the efficacy of function-based intervention for young children at-risk for emotional and behavioral disorders (EBD) in inclusive environments. Participants were two kindergarten students and one first-grade student, all of whom exhibited chronic disruptive behavior in the classroom despite previous interventions implemented through their school's existing behavioral support system. The study was conducted across three phases: (a) a descriptive functional behavioral assessment (FBA) was completed for each student, (b) a systematic process was used to construct and then test individualized interventions, and (c) the interventions were then provided to each student during his most problematic classroom activity using a multiple baseline design. Classroom interventions substantially improved the on-task behavior of each student, and social validity ratings by teachers showed strong preference for the function-based intervention over the previously used classroom practices. Implications, limitations, and directions for future research are presented. (Contains 3 tables and 2 figures.)