The present study used a context-based model of assessment and intervention to explore whether interventions that modify context result in reduction of problem behavior in ecologically valid settings (i.e., typical routines implemented by typical education personnel in neighborhood schools). The Contextual Assessment Inventory (CAI) and a postassessment interview were administered to parents and teachers of eight children with Autism Spectrum Disorder to identify problem contexts. Then, environmental modification techniques were implemented in three priority contexts: namely, transitions, termination of preferred activities, and presence of a feared stimulus. Our results demonstrated an almost complete elimination of problem behavior in the priority contexts as well as successful completion of activities and routines related to those contexts. We discuss the value of conceptualizing problem behavior as a function of context with respect to facilitating both assessment and intervention, and the need for enhancing breadth of effects to determine the larger impact of a context-based approach on promoting meaningful behavior change in the community. (Contains 2 tables and 3 figures.)