ABSTRACT We report two studies investigating whether relationship satisfaction differentially influences the use of the “self-based heuristic” (SBH) or the degree to which an individual's own characteristics contribute to ratings of another's personality. Individuals rated themselves, a friend, and a person with whom they have experienced significant conflict (a “foe”); ratings were made on measures of the Big Five and trait affectivity. Replicating previous research, judges made greater use of the SBH when rating trait affectivity than when rating the Big Five. In addition, individuals were more likely to utilize the SBH when rating friends than when rating foes. Further, relationship satisfaction made significant independent contributions in accounting for the variance in trait ratings of others. These findings extend our understanding of the mechanisms involved with person perception beyond observable trait-related information.