Background. Children with either underweight or overweight may be at risk for mental health problems and require mental health service use. The present study investigated the relationship between weight status and psychosocial dysfunctioning in children of two different age groups (5–6 and 13–14 years). Methods. Using height and weight measurements collected during routine medical examinations of all children in a circumscribed geographical region, measures of underweight and overweight were calculated in young children (aged 5–6 years; n=797) and in adolescents (13–14 years; n=614). In addition, parent-reported questionnaires (young children) and adolescent-reported questionnaires (adolescents), including the Strengths and Difficulties Questionnaire (SDQ), provided information on psychopathology subscales including emotional symptoms, conduct problems, hyperactivity-inattention, peer problems and prosocial behaviour. Results. Few associations were apparent after controlling for confounding variables. Young children who were underweight (but not severely underweight) less frequently displayed conduct problems, while adolescents who were overweight or obese reported more peer problems and less prosocial behaviour than did children of normal weight. Children who were underweight and children who were overweight did not score higher on any of the other psychopathology scales than did children of normal weight in either age group. Conclusion. Our findings suggest that the domains of weight problems and psychopathology do not display strong associations. However, there are indications that some areas of psychopathology may be differentially associated with weight problems. Further longitudinal research is warranted.