This study combined a number of behaviour modification strategies into a programme aimed at changing behaviours of delinquent and acting out children. The programme was used at Duffield Place, a small special school where such children were referred when it was deemed that they could no longer be catered for in their home schools. An examination was made of the five main theories of delinquency (Psychoanalytic, Biological, Conditionability, Sociological and Social Learning) and seven behavioural procedures commonly used with delinquent and acting-out children (systematic adult attention and feedback, token economies, contracting, stimulus change, assertiveness training, time out and generalization training). The first seven children to finish the programme in 1981 were then examined, using a case study approach, to answer two questions - 1. Can acting out and delinquent children be removed from their home schools and be taught various skills that will generalize when they are returned to a home school? 2. Can the. programme be assessed by the staff and consultants working at the centre? Criteria used to evaluate effectiveness were the number of offences involving police contact, whether the child remained in school until he or she was fifteen years old, whether the home school reported a decrease in aggressive/disruptive behaviours and whether there was an increase in measured self-esteem and attainments. Most criteria were met with most children and maintained so the evaluation met the needs of the public schools system. However functional relationships between particular interventions and behaviour changes were not established and evaluation by personnel other than those at the centre would be necessary to establish these relationships. Results from programmes like that at Duffield Place should provide a more complete theoretical basis for working with delinquent and acting-out children.