Attempts to identify people at imminent risk of psychotic disorder have been made during the past 20 years. High-risk criteria have been developed, and despite findings of a recent decline in the rate of onset of psychosis associated with these criteria, people identified still have a significantly greater risk, compared with the general population. Intervention studies in this group indicate that psychological treatments and fish oil appear to be just as effective as antipsychotics. Future research should refine risk factors for psychosis and examine outcomes other than psychosis. Research is also needed into what harms and benefits are associated with making the high-risk criteria into a formal diagnosis.