Ubiquitous to theories of social perception is an assumed relationship between an attribute’s (e.g., intelligence) “signal” and judgment accuracy, with accuracy impossible without the presence and consensual use of signal. Yet this foundational assumption remains untested. Our investigation focused on consensus (quantified using intraclass correlations, ICCs), which should suggest signal availability, according to theories of accurate social perception. Study 1 confirmed that judgments of different social attributes exhibit different degrees of consensus. Study 2 specifically tested the consensus → accuracy link, anticipating that social judgments with higher consensus (target ICCs) would show greater judgment accuracy. Using 497,780 judgments of 3,847 targets from 4,162 participants across 45 data sets testing a broad variety of social judgments, we found that consensus moderated the relationship between targets’ self-report and participants’ judgments: Judgment accuracy was higher when consensus was higher. Results show the first empirical support for a foundational assumption of theories of social perception.