Confidence in personality impressions is proposed to stem from the richness of people's mental representations of others. Representational richness produces confidence because it enhances the fluency with which people can make judgments, and it increases confidence even when it does not result in more accurate impressions. Results of 3 experiments support these propositions. A 4th experiment suggests that representational richness is increased by both pseudorelevant and relevant information, but not by irrelevant information. A 5th experiment suggests that representational richness has effects on confidence above and beyond the effects of metainformation (i.e., extracontent aspects of information). The implications of these findings for evaluating evidence of error in person perception and for reducing stereotyping and prejudice are discussed.