The vast majority of closed-head injuries (CHI) in children are of mild severity. Even if only a small proportion of children with mild CHI suffer persistent negative outcomes, then mild CHI is a serious public health problem. This paper summarizes the existing literature regarding the neurobehavioural outcomes associated with mild CHI in children and adolescents, focusing on the longstanding debate regarding post-concussive syndrome. The paper also discusses conceptual and methodological issues that arise in research on the outcomes of mild CHI, including the definition of mild CHI; selection of comparison groups; measurement of outcomes; assessment of risk factors; timing of outcome assessments; and prediction of outcomes for individual children. The paper describes an ongoing research project that may help to resolve some of the longstanding controversies and uncertainties regarding the outcomes of mild CHI in children and concludes with a review of likely future directions for research on the outcomes of mild CHI. The long-term goal of research in this area is to develop a comprehensive and integrated biopsychosocial model of outcomes that can help guide clinical management.