The tip-of-the-tongue experience (TOT) has intrigued psychologists for nearly a century. R. Brown and McNeil (1966) provided the first systematic exploration of the phenomenon, and the findings since their seminal study suggest that TOTs (a) are a nearly universal experience, (b) occur about once a week, (c) increase with age, (d) are frequently elicited by proper names, (e) often enable access to the target word's first letter, (f) are often accompanied by words related to the target, and (g) are resolved during the experience about half of the time. Important questions remain concerning TOTs: (a) Are emotional reactions necessary, (b) do only low frequency targets elicit TOTs, (c) do TOTs reflect incomplete target word activation or interference from related words, and (d) do spontaneous retrievals really occur? A more precise definition of the TOT experience is needed, as well as greater uniformity in the information gathered during TOTs.