Purpose: Wisdom has received increasing attention in empirical research in recent years, especially in gerontology and psychology, but consistent definitions of wisdom remain elusive. We sought to better characterize this concept via an expert consensus panel using a 2-phase Delphi method. Design and Methods: A survey questionnaire comprised 53 Likert scale statements related to the concepts of wisdom, intelligence, and spirituality was developed to determine if and how wisdom was viewed as being distinct from the latter 2 concepts. Of the 57 international wisdom experts contacted by e-mail, 30 completed the Phase 1 survey and 27 also completed the Phase 2 survey. Results: In Phase 1, there were significant group differences among the concepts of wisdom, intelligence, and spirituality on 49 of the 53 items rated by the experts. Wisdom differed from intelligence on 46 of these 49 items, whereas wisdom differed from spirituality on 31 items. In Phase 2, we sought to define wisdom further by selecting 12 items based on Phase 1 results. Most experts agreed on many of the suggested characteristics of wisdom--that is, it is uniquely human; a form of advanced cognitive and emotional development that is experience driven; and a personal quality, albeit a rare one, which can be learned, increases with age, can be measured, and is not likely to be enhanced by taking medication. Implications: There was considerable agreement among the expert participants on wisdom being a distinct entity and a number of its characteristic qualities. These data should help in designing additional empirical research on wisdom.