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Three participants with moderate to profound mental retardation were exposed to choices between an immediate small amount and a delayed larger amount of a preferred rein-forcer. All participants initially showed a relatively high preference for the smaller rein-forcer, suggesting impulsive choice making. However this preference reversed, suggesting self-control, when the larger reinforcer was available immediately and, over time, its delay was gradually increased. Results highlight the potential utility of incorporating concurrent activities into self-control training paradigms. DESCRIPTORS: choice, delayed reinforcement, developmental disabilities, impul-sivity, self-control Self-control, or selecting the larger de-layed reinforcer over a smaller immediate one, can be enhanced by either a gradual increase in the length of the delay-to-rein-forcement interval preceding the larger re-inforcer (Schweitzer & Sulzer-Azaroff, 1988) or by requiring the participant to engage in some intervening activity during the dela