The goal of this study was to examine the effect of physical modifications on the academic engagement and disruptive behavior of Deaf or Hard-of-Hearing students in self-contained classrooms. Three classrooms at a school for the Deaf were modified after consultation with the classroom teachers. The modifications of the classroom environment included changes in seating arrangements, classroom organization, visual stimulation, and acoustic quality. A multiple-baseline design was used to examine the effects of the intervention on the frequency of student academic engagement and disruptive behaviors. Results show a functional relationship between the physical environment and both an increase in levels of academic engagement and a decrease in levels of disruptive behavior. Teachers maintained the majority of modifications after the study ceased. Social validity ratings by the teachers indicated high acceptability of the intervention. Limitations and practical implications for future research are discussed.