Variations between people’s personalities, skills and abilities are a usual and, in many respects, valuable aspect of life. But a few individuals’ mental capacities in areas like simple calculation or the co-ordination of complex movements fall far short of average standards. Such people may as a result be in some ways disadvantaged as compared with their contemporaries and so considered to be mentally handicapped.

A more precise definition of mental handicap would be difficult to establish. It has many causes and its manifestations cover a considerable range of levels of capability. A minority of retarded individuals are totally unable to care for themselves. But others on the arbitrary border line between normality and sub-normality may only experience slight limitations in their day-to-day lives, some perhaps caused through their unfortunately being labelled as mentally handicapped during their school careers.

Yet despite the disparate specific degrees and types of disabilities suffered most mentally handicapped people share certain underlying problems and needs, such as those related to finding a suitable occupation. For these to be adequately understood it is first necessary that the distinction between mental handicap and mental illness should be clearly understood. The latter is a usually temporary state of distressing, abnormal consciousness experienced by people who generally have average mental abilities. The term mental handicap refers to the normal level of functioning (which may or may not be subject to modifications through learning) of individuals with certain limited mental capacities. Given the right opportunities in life they need not experience any special distress or disturbance.

Current work on mental handicap centres both on ways of preventing its occurrence and on ways of meeting the social and educational needs of those affected. This paper examines and relates aspects of these two subjects, paying particular attention to the possibilities of preventing the more severe forms of mental retardation, after first looking at the abilities of the handicapped and the causes of their condition.