Conduct disorder (CD) is estimated to affect 5-10% of children aged 5-15 years in the United Kingdom and the United States. For those children with early onset in pre-school years, CD frequently persists into adulthood, and predicts poor employment prospects, marriage breakdown and self-harming and/or anti-social criminal behaviour. The economic implications of severe behavioural problems in childhood are serious. It has been estimated that by age 28 the costs of publicly resourced services for those with conduct disorder in childhood were 10 times higher (?70,019) than for those with no behavioural problems (?7,423). Parenting is a key determinant in child behaviour. Parents who encourage pro-social behaviour have children with fewer behaviour problems. Parenting-training programmes are effective in helping families with children at risk of developing conduct disorders.