AIM: To establish a comprehensive phase-oriented early intervention service for young people with early psychosis in south London and to evaluate its effectiveness in delivering user friendly interventions and better outcomes. METHODS: The Lambeth Early Onset (LEO) and Outreach & Support in South London (OASIS) service has been developed incrementally over the last 6 years into 4 teams each addressing one of the phases of early psychosis: (i) prodrome/ultra-high risk (ii) untreated psychosis (c) acute inpatient treatment and (d) recovery/ relapse prevention phases. Research and evaluation have been integral to each team's development with three of the teams configured as Randomised Controlled Trials. RESULTS: During the first 6 years, 1255 young people in Lambeth were referred for assessment (963 to LEO and 292 to OASIS). Of them 578 were diagnosed as suffering from first episode psychosis (some before or after they presented to OASIS), 450 have been followed up in Lambeth by the LEO Community Team and 40% discharged back to GPs in remission at the end of their two years of follow-up. Compared to standard service, patients' delays in accessing treatment are less, and outcomes at 18 months are better. CONCLUSIONS: The LEO and OASIS service now provide most of the mental health service requirements for young people with early psychosis in Lambeth. It represents good value for money and improved outcomes for clients. Further interventions are planned and ultimately it will be possible to evaluate the impact of each incremental step in the service's development.