We examined the effect of acquaintanceship on interjudge agreement in personality ratings. Approximately 150 undergraduates described their own personalities using the Q-sort. They were also described by two close acquaintances and by two "strangers" who knew them only via a single, spontaneous interaction viewed on videotape. The effect of acquaintanceship was powerful: Judgments by close acquaintances agreed with each other and with subjects' self-judgments much better than did judgments by strangers, even though strangers' judgments agreed with each other and with subjects' self-judgments beyond a chance level. This result implies that agreement among acquaintances' judgments must derive at least partly from experience with and observation of the person who is judged. The same traits that yielded better agreement among acquaintances also yielded better agreement among strangers and tended to be rated higher in subjective visibility, suggesting that people are intuitively knowledgeable about the traits they can judge with more and less agreement.