The rapidly growing interest in early psychosis has three preventive foci. The prepsychotic phase is when most psychosocial impairment develops, but the specifics of treatment remain difficult to research and apply. Although the total duration of untreated illness may be more critical, the duration of untreated psychosis is a more realistic immediate target for strategies of early detection and intervention. The role of duration of untreated psychosis as a causal factor influencing outcome remains to be definitively established, but these strategies are well justified on clinical grounds. Finally, first-episode psychosis is comparatively more treatment responsive than multiepisode psychosis, and intensive phase-specific treatment appears to result in short-term improvements in outcome and cost effectiveness. (C) 2000 Lippincott Williams and Wilkins.