Both Attention-Deficit/Hyperactivity Disorder (AD/HD) and divorce are very prevalent in western societies, and they may occur together. AD/HD is generally viewed as a neurobiological disorder, which has led to a commonly held belief that social-environmental factors play little role in the symptom profile of children diagnosed with the disorder. This study investigated the association between parental divorce, remarriage, multiple transitions, the quality of relationships with family members and the psychological well-being of children and adolescents with AD/HD. First, differences in children’s AD/HD symptom profiles in relation to parents’ divorce status (single/multiple divorce) and family composition (single parent/stepfamily) were examined. Second, the association between the quality of children’s relationships with each family member and parents’ marital status (divorced/non-divorced) and family composition was investigated. In addition, age, gender and AD/HD subtype differences were assessed. Third, the association between the quality of children’s interactions with family members and children’s AD/HD symptom profile was explored. No significant differences in children’s behavioural profiles were found in terms of parents’ divorce status. Living in stepfamilies was associated with greater AD/HD severity and social malfunctioning. Disruptive parent–child and sibling relationships were found to be related to children’s age, gender, AD/HD subtype and parents’ marital status. Further, poor interactions with family members correlated with children’s AD/HD severity and psychological well-being. In summary, divorce, remarriage and the quality of relationships with family members are important correlates of the symptom profile of children with AD/HD, and this emphasises the need for special treatment modules for these families.