AbstractPatients' expectations have long been considered a contributory factor to successful psychotherapy. Expectations come in different guises, with outcome expectations centered on prognostic beliefs about the consequences of engaging in treatment. In this article, we define outcome expectations and present assessment methods and clinical examples of outcome expectations. Our research review includes a comprehensive meta‐analysis (N =8,016 patients across 46 independent samples) of the association between pretherapy or early‐therapy outcome expectations and posttreatment outcomes. The overall weighted effect size was d=.24, p<.001, indicating a small but significant positive effect of outcome expectations on adaptive treatment outcomes. We also provide a narrative review of mediators of the expectation‐outcome link and patient factors that relate to their outcome expectations. Finally, we discuss limitations of the research base and offer therapeutic practices based on our findings. © 2010 Wiley Periodicals, Inc. J Clin Psychol: In Session 67:184–192, 2011.