In the 1970s, memory researchers converged on interesting phenomena observed in Korsakoff-syndrome amnesic patients. These patients’ performances on difficult tasks were reliably improved by practice sessions from which they could recall nothing. Related findings of indirect memory effects in college students triggered wide attention to phenomena that, in 1985, were first identified as implicit memory. Within a decade, the indirect measurement methods of implicit memory research had spread to social psychologists’ studies of attitudes and stereotypes. After another two decades, the methods and findings of this developing revolution have revised understanding of how past learning, operating in ways that bypass conscious awareness, nevertheless shapes conscious judgment and perception. This revolution in psychological thinking is on the cusp of reconceiving the relation between unconscious and conscious mental process. Further, it demands researchers’ careful attention to justification for many self-report measures that are now routinely treated as face-valid.