The bulk of personality research has been built from self-report measures of personality. However, collecting personality ratings from other-raters, such as family, friends, and even strangers, is a dramatically underutilized method that allows better explanation and prediction of personality's role in many domains of psychology. Drawing hypotheses from D. C. Funder's (1995) realistic accuracy model about trait and information moderators of accuracy, we offer 3 meta-analyses to help researchers and applied psychologists understand and interpret both consistencies and unique insights afforded by other-ratings of personality. These meta-analyses integrate findings based on 44,178 target individuals rated across 263 independent samples. Each meta-analysis assessed the accuracy of observer ratings, as indexed by interrater consensus/reliability (Study 1), self-other correlations (Study 2), and predictions of behavior (Study 3). The results show that although increased frequency of interacting with targets does improve accuracy in rating personality, informants' interpersonal intimacy with the target is necessary for substantial increases in other-rating accuracy. Interpersonal intimacy improved accuracy especially for traits low in visibility (e.g., Emotional Stability) but only minimally for traits high in evaluativeness (e.g., Agreeableness). In addition, observer ratings were strong predictors of behaviors. When the criterion was academic achievement or job performance, other-ratings yielded predictive validities substantially greater than and incremental to self-ratings. These findings indicate that extraordinary value can gained by using other-reports to measure personality, and these findings provide guidelines toward enriching personality theory. Various subfields of psychology in which personality variables are systematically assessed and utilized in research and practice can benefit tremendously from use of others' ratings to measure personality variables.