Background: This paper reviews recent evidence on the causes and maintenance of aggressive and disruptive behaviours in childhood and adolescence. It considers the relative merits of several different ways of conceptualising such problems, in relation to the contribution of biological, psychological and social factors. Method: It focuses on conduct problems appearing in young childhood, which greatly increase the likelihood of persistent antisocial behaviours in adolescence and adult life in association with wider interpersonal and social role impairments. It considers the contribution of individual factors, including impaired verbal skills, deficits in executive functions, and an imbalance between behavioural activation and inhibition systems. These are viewed in interaction with commonly associated environmental disadvantages such as hostile or intrusive parenting. The roles of attributional biases, unrealistic self-evaluations, and insecure attachment are considered in relation to affect regulation, and effective social action. The contributions of the wider social environments of peers, neighbourhood and socio-economic conditions are evaluated. Conclusions: The paper concludes that, although considerable progress has been made over the past ten years, there is a need to further refine our conceptualisation of the behaviours to be explained, to develop a coherent theory of the causal and maintaining processes, and to carry out prospective studies with adequate numbers of high risk children.