Oppositional behaviours in children and adolescents present significant challenges for parents, educators, paediatricians, and mental health professionals. These behaviours vary in intensity from mild noncompliance to severe defiance and refusal, with persistent and pervasive oppositional behaviours significantly impacting a child’s or adolescent’s immediate and subsequent academic and socioemotional functioning, hindering the delivery of necessary health examinations or medical care, and violating conventional social norms. Children and adolescents with atypical oppositional behaviours have the potential to face lifelong challenges with authority or in social settings. There is currently insufficient evidence regarding the efficacy of pharmacological treatment for disruptive, oppositional, or conduct issues in children beyond the management of overt aggressive behaviour and impulsivity, with concerns about side effects. Non-pharmacological interventions should be explored as the first-line approach for managing oppositional behaviours. A comprehensive investigation of the child or adolescent of their comorbid and/or underlying psychiatric and neurodevelopmental conditions, developmental and socioemotional needs, and familial or environmental influences, will allow for specific, tailored, and optimised treatment. Interventions to manage clinically significant oppositional behaviours require an integrated, transdisciplinary effort including the psychological, psychosocial, psychiatric, and medical disciplines together with the child and adolescent and their family and friends.