Students with disabilities often have large vocabulary deficits that continue to increase over time if effective interventions that supplement daily academic instruction are not put in place. The current study used a simultaneous treatments design to analyze the comparative effects of whole-word vocabulary instruction and morphograph instruction on students' vocabulary acquisition and generalization through the use of a computer-assisted peer-tutoring program. Seven of eight middle school participants with mild disabilities involved in this study acquired higher percentages of vocabulary in the morphograph condition compared to the whole-word condition. All eight students were better able to generalize to unknown vocabulary in the morphograph condition. This study's findings indicate a functional relationship between morphograph instruction and the acquisition and generalization of vocabulary. (Contains 1 table and 6 figures.)