Abstract
Individualization of instructional programs, a concept deeply ingrained in special education, rests in part on the assumption that some kinds of instruction are better for some students while other kinds are better for other students. In research, differentiation of instruction based on learner characteristics is called “aptitude-treatment interaction.” This article examines various models of aptitude-treatment interaction that guide these studies, with specific reference to individualization of instruction for special education pupils. The examination reveals scant evidence to support the notion of individualization.