Primary school-aged children with conduct problems are at risk of future antisocial and criminal behaviour, particularly when there are additional family-level risk factors. However, little is known about how school-related factors can reduce that risk. This qualitative longitudinal study investigates school-related influences on changes in the behaviour of at-risk children in high-need families over a period of 5 years. Families of 11 children with serious behaviour problems were followed over the transition to secondary school. In-depth interviews with mothers, and with practitioners who support the child or family, explored school-related factors which appeared helpful or unhelpful in improving children's behaviour over time. The analysis found that the disjuncture between the nurture experienced at primary school and a lack of nurture later at secondary school was problematic. Children tended to change primary school until they found one prepared to offer them a high level of nurture and supervision. Consistent relationships with supportive adults were important, but were rare after the transfer to secondary school. Literacy problems remained unrecognised or unaddressed for too long, contributing to children's lack of engagement. Inconsistent disciplinary responses to minor behaviour issues tended to escalate problems and most children were eventually excluded from mainstream education. Communication between parents and school staff was often problematic; parents sometimes experienced school contacts as burdensome, ill-informed and unsupportive. However, good communication could aid development of successful approaches to supporting children with difficult behaviour.