Abstract This paper summarizes certain aspects of an assessment of the level of the moral judgement of three groups of children: mildly educationally subnormal children, ESN(M), who are also maladjusted; stable ESN(M) children; and stable children of approximately average intelligence. A minimum age of 12.0 years was stipulated; all the children attended secondary school with the oldest in the total sample being 15 years 9 months. The assessment procedure which, although owing much if not all of its rationale to Piaget, is original in its mode of presentation and largely in its content, is described. The results of each of the three groups are compared. Also, the results are correlated with IQ. This enables a judgement to be arrived at as to the relative importance of (a) intelligence and (b) social adjustment in the making of mature moral decisions and choices.