This review examines the clinical and theoretical evidence justifying early intervention in individuals with schizophrenia. Potential reasons for the previous lack of emphasis on early intervention are discussed. Interventions that target psychosis are distinguished from those that work on prodromal symptoms. It is suggested that early intervention programmes should try to reduce the duration of untreated psychosis. The relationship between this and outcome is discussed. Improving service accessibility alone may not be sufficient, and education and destigmatisation input may be required. Once a patient is identified, vigorous pharmacological and psychosocial interventions are important to improve the long-term clinical outcome. An effective early intervention programme for psychosis provides a basis for the future development of a prodrome intervention programme.