A group of severely retarded institutionalized adults was exposed to three different types of instructional procedures (imaginal instruction, verbal instruction, no instruction) and three types of reinforcement procedures (no reinforcement, reinforcing correct responses, reinforcing all responses) in learning concepts through modeling. Concept acquisition was tested, using Leiter-type items, in direct imitation as well as in a generalization task. In both imitation and generalization conditions, imaginal instructions were more effective than verbal instructions, which in turn were more effective than no instructions. The study of modeling procedures, especially with regard to the use of imagery, is called for in order to investigate the processes involved in their effectiveness with a severely retarded population.