The value of monitoring for prodromal symptoms in patients with schizophrenia has been questioned by some investigators who point out that their positive predictive value, sensitivity, and specificity can be low in relation to relapse. This article focuses on methodological and conceptual issues which should be considered in evaluating the usefulness of prodromal symptoms and behaviors as part of the relapse process. The article presents the following conclusions: Many relapses are preceded by the appearance of prodromal symptoms and behaviors which may last from a few days to a few weeks or more. The presence of prodromal symptoms often does not predict impending relapse since the probability of progression to relapse depends on the complex interaction of many personal and environmental factors including the availability of prompt and effective psychiatric intervention. Finally, studies have shown that monitoring for prodromal symptoms and early intervention when they emerge is effective in reducing the likelihood of relapse in individuals with schizophrenia.