In previous research, tasks involving stimulus discrimination and simple learning were related to computer-assisted sight-word learning by moderately retarded adolescents (Conners & Detterman, 1987). The authors suggested that if these abilities interacted with specific instructional variables to determine word learning, such interactions might be useful in designing individualized computer-assisted instruction for mentally retarded students. In the present study interactions of these two abilities with two specific instructional variables were investigated. An interaction was found between stimulus discrimination and the number of words presented at one time for learning. Results were interpreted within Anderson's (1982) model of declarative and procedural knowledge.