Chronic psychosis, as for instance schizophrenia, usually begins in young adulthood and may cause severe disability. It causes a mean loss of life expectancy of 22 years.Actual models of psychosis do not trace the beginning of psychosis to the first franc psychotic episode only, but to earlier symptoms.In a classical health system only considering the first psychotic episode, the mean duration of untreated illness (DUI) can last several years. Yet this DUI has a direct impact on the prognosis of the disease.Actual international recommendations prescribe to early detect and treat at risk mental states of psychosis, thus reducing DUI. Such an attitude also helps the patient to integrate care in a moment where she/he is fully in condition to consent and to adhere.Generalist practitioners are crucial actors of early detection. We describe here simple and standardized tools helping early detection of high-risk mental states of psychosis in primary care and the appropriate attitude to do it properly.Numerous countries have developed early detection and treatment centers for psychosis. It has been established that such interventions clearly decrease the risk of transition towards chronic psychosis and improve the prognosis.These recent data about early detection and intervention in psychosis are a major step forward in psychiatry practice. It is now necessary to largely develop such actions in France.