Childhood behavioural problems have been defined in many ways, but in the context of this article, they refer to 'acting out' behaviours, such as aggressive behaviour and non compliance. In order to identify children at risk of difficulties, and to intervene effectively, an understanding of the factors influencing the development of children's behavioural problems is vital. Two of the main factors implicated in the development of behavioural problems are child temperament and parenting. This article describes the results of the Social Development Project, a study that aims to investigate the role of temperament, parenting and social context in the development of behavioural and emotional problems. Recent findings from the project suggest that temperament and parenting style are important influences on child adjustment, and that the best style of parenting may differ for children with different temperaments.