In this study, observers' abilities to detect lies in children and adults were examined. Adult participants observed videotaped interviews of both children and adults either lying or telling the truth about having been touched by a male research assistant. As hypothesized, observers detected children's lies more accurately than adults' lies; however, adults' truthful statements were detected more accurately than were children's. Further analyses revealed that observers were biased toward judging adults' but not children's statements as truthful. Finally, consistent with the notion that there are stable individual differences in the ability to detect lies, observers who were highly accurate in detecting children's lies were similarly accurate in detecting adults' lies. Implications of these findings for understanding lie-detection accuracy are discussed, as are potential applications to the forensic context.