ABSTRACTPeople with profound mental handicaps have in the past been described as behaviourally incompetent or even “vegetative” (Fuller, 1949). Descriptions of this kind convey a belief that such people are incapable of learning or responding to environmental change. Over the last 30 years, however, this view has been challenged and rejected. In both laboratory and applied settings, people with profound mental handicaps have been shown capable of behavioural adaptation and learning. This article first provides an overview of the literature and then examines more recent theoretical work on learning and performance in conditioning situations and the relevance of this work in the treatment and remediation of profound mental handi