This study provides a demonstration of the process of positive behavior support (PBS) within a home setting to address the challenging behavior of a sibling set within family routines. Although a growing data base is demonstrating the feasibility and effectiveness of conducting functional behavioral assessment and implementing assessment-based interventions for young children in family contexts, the vast majority of these studies have focused on dyadic parent-child interactions. The presence of more than one child, particularly when all children display challenging behaviors, can amplify levels of parent stress and complicate the logistics of assessment, planning, and systematic intervention. In this study, three young children presented challenging behaviors that were highly disruptive to home routines. Functional assessments were followed by implementation of multicomponent, family-centered PBS plans individualized to four activity routines. Multiple-baseline across-routines and quasiexperimental (A-B) within-routines designs demonstrated promising effects of the interventions in reducing aggregate levels of challenging behavior.