This article reviews research that examines the effects of relationship expectations on interpersonal relationships. Most of the published research suggests that positive relationship expectations are associated with better interpersonal functioning, as indicated by greater relationship persistence, more positive relationship evaluations and motivations, more prorelationship behavior, more forgiveness, and reduced contempt. Research on related constructs, such as relationship efficacy, implicit theories, trust, and insecurity dispositions, suggests a similar conclusion. However, there is some evidence that positive relationship expectations may sometimes have negative effects on healthy relationship functioning. A model of the multiple pathways through which relationship expectations may promote and threaten relationship quality is described, and several directions for future research are suggested.