Self- and other-ratings on the Big Five and a comprehensive inventory of trait affect were obtained from 74 married couples, 136 dating couples, and 279 friendship dyads. With the exception of Surprise, all scales showed significant self-other agreement in all 3 samples, thereby establishing their convergent validity. Consistent with the trait visibility effect, however, the Big Five consistently yielded higher agreement correlations than did the affectivity scales. Conversely, the affective traits consistently showed stronger evidence of assumed similarity (i.e., the tendency for judges to rate others as similar to themselves) than did the Big Five. Cross-sample comparisons indicated that agreement was significantly higher in the married sample than in the other 2 groups; however, analyses of 3 potential moderators in the dating and friendship samples failed to identify the source of this acquaintanceship effect.