Attenuated and transient psychotic symptoms as well as a combination of different risk indicators and a recent significant deterioration in global functioning are currently used as a preliminary definition of the initial prodromal or at-risk mental state by the vast majority of investigators in research on early psychosis detection and intervention. Recently published results demonstrated a mean progression to frank psychosis within one year in 36.7 % of cases showing emerging symptoms, indicating that these criteria already seem to provide a satisfying assessment for risk of an imminent psychosis. However, as functional decline often sets in before this time, detection in earlier prodromal stages seems necessary. In a prospective study, certain basic cognitive and perceptive symptoms showed good to excellent predictive accuracy for schizophrenic psychosis, thus potentially offering a reasonable approach for earlier detection. Early intervention is aimed at improving prodromal symptoms, avoiding functional deterioration, and suppressing or delaying transition to psychosis. Initial study results targeting an earlier or later prodromal phase are promising, but longer follow-ups and larger samples are needed.