Early-onset psychosis (EOP) is a severe mental disorder with a significant impact on affected children, young people and their families. Its assessment and diagnosis may be challenging, treatment approaches may not always lead to full remission of symptoms, and it is frequently associated with recurrent episodes and long-term disability. A comprehensive evaluation of psychotic symptoms, co-morbidities, physical health and environmental risk factors is likely to contribute to the holistic understanding of the child or adolescent with psychosis and provide the best possible management framework. A systematic approach to treatment with antipsychotic medication and psychosocial interventions should incorporate regular reviews of its effectiveness and adverse effects. Early intervention seems to lead to optimal outcomes through reducing the duration of untreated psychosis and providing input during the critical period after its onset when treatment can be most effective. Further research aiming to advance our understanding of the complex aetiology of psychotic disorders, effectiveness of management strategies, and necessary service provision is urgently needed.