The natural history of schizophrenia is often chronic and debilitating, an enduring fact that draws attention to the first episode and early course of the disorder when neurobiological deficits apparently form. Many recent studies have focused on the duration of untreated psychosis (DUP) in first-episode patients for reasons that are reviewed here. DUP is often months or years in length, making it a major public mental health problem. Reducing DUP through early detection may be possible from a service systems perspective. This may be very important because earlier treatment not only reduces acute psychotic symptoms, but may also improve long-term prognosis by attenuating the deficit processes active at this time; processes that are either signaled by or a product of DUP. Finally, DUP appears to influence sampling in first-episode research in that longer DUP is associated with higher recruitment refusal rates to studies. For all of these reasons, DUP should be added to the battery of descriptive variables routinely collected on all patients with schizophrenia, whether for treatment or research.