Early intervention services were established on the basis of a number of fundamental principles, including the notions that intervening in the early stages of psychosis alters illness trajectory and prognosis, that multicomponent interventions promote psychosocial recovery and reduce iatrogenic damage, and that early targeting of non-responders reduces treatment resistance. There is growing evidence of the benefits of specialised early intervention services. These include improved clinical, social and vocational outcomes, reduced in-patient stays and better engagement. Early intervention services can also significantly reduce the risk of a second episode and are highly valued by service users and carers. Duration of treatment appears to determine long-term outcome and there remains uncertainty about how long such intensive intervention should last and whether all patients need the same length of care. Budgetary constraints are pervasive and are particularly likely to affect prodrome clinics and community awareness programmes.