Effective population-based early intervention to improve the functioning of with antisocial behaviour is practically feasible by targeting multiple risk factors and emphasising implementation fidelity.

Programs can be organized to be engaging and effective in improving parenting among high-risk, multi-ethnic communities, which is of considerable value. To also be cost-effective in achieving child changes may require a set-up that enables parents to attend more sessions and/or an exclusive focus on children with clinically significant behavior problems.

Objective To see whether a behaviourally based group parenting programme, delivered in regular clinical practice, is an effective treatment for antisocial behaviour in children. Design Controlled trial with permuted block design with allocation by date of referral. Setting Four local child and adolescent mental health services. Participants 141 children aged 3-8 years referred with antisocial behaviour and allocated to parenting groups (90) or waiting list control (51). Intervention Webster-Stratton basic videotape programme administered to parents of six to eight children over 13-16 weeks. This programme emphasises engagement with parental emotions, rehearsal of behavioural strategies, and parental understanding of its scientific rationale. Main outcome measures Semistructured parent interview and questionnaires about antisocial behaviour in children administered 5-7 months after entering trial; direct observation of parent-child interaction. Results Referred children were highly antisocial (above the 97th centile on interview measure). Children in the intervention group showed a large reduction in antisocial behaviour; those in the waiting list group did not change (effect size between groups 1.06 SD (95% confidence interval 0.71 to 1.41), P < 0.001). Parents in the intervention group increased the proportion of praise to ineffective commands they gave their children threefold, while control parents reduced it by a third (effect size between groups 0.76 (0.16 to 1.36), P = 0.018). If the 31 children lost to follow up were included in an intention to treat analysis the effect size on antisocial behaviour was reduced by 16%. Conclusions Parenting groups effectively reduce serious antisocial behaviour in children in real life conditions. Follow up is needed to see if the children's poor prognosis is improved and criminality prevented.

Background: Youth offending and antisocial behavior (ASB) are associated with low