To the Editor: Aging well—successful aging and related concepts (healthy, optimal, active, positive, aging)—is a relatively new domain of research in the study of aging.1 The literature on successful aging reveals a wide range of definitions, most of them reflecting only one theoretical, academic, or scientific field and therefore being partially biased. Thus, biomedical researchers mainly emphasize health and physical functioning; psychologists usually limit their interest to subjective dimensions such as life satisfaction or well-being, and social scientists usually consider socioeconomic conditions the key aspects of successful aging. Nevertheless, because aging implies a biopsychosocial process, successful aging must be considered as an interdisciplinary subject of inquiry and a multidimensional concept. But successful aging—or in lay vocabulary, "aging well"—is also a concept in the mind of the people. Older adults' views of aging well is an important avenue of inquiry, because it is helpful in testing to what extent a scientific concept has been disseminated through different continents, countries, and cultures and because this familiarity is required for engaging elderly people (in different part of the world) in practices or programs that promote aging well. Trying to make cross-cultural comparisons of elderly people's views, the same 20-item questionnaire (plus a rank order for selecting the five most-important aspects) used by Phelan et al.2 and Matsubayashi et al.3 was administered to elderly adults in seven Latin American (Brazil, Chile, Colombia, Cuba, Ecuador, Mexico, and Uruguay) and three European (Greece, Portugal, and Spain) countries. A sample of 1,189 elderly adults (495 men and 694 women; mean age 68.2) participated in this study (unpublished data). The reliability coefficient of the questionnaire used was high (α=0.89). To identify differences between countries, item-by-item and country-by-country comparisons were made; minor significant differences were found (<10% of the total comparisons). Therefore, to make comparisons between the results of the current study and those reported by Phelan et al. (Japanese-American and white American participants), and Matsubayashi et al. (Japanese participants), the results from the current study from Latin-American and European countries are reported. Table 1 shows the percentage of respondents who rated each item as important in successful aging. Following Phelan et al. and Matsubayashi et al., a cutoff of 75% or more respondents estimated as important differs from 7 items in the Japanese sample to 19 in the Latin American sample, whereas Japanese Americans, white Americans, and European samples, respectively, rated 13, 14, and 16 of the 20 attributes as important. There was a major consensus in all samples or individuals assessed in a given country regarding items 2 (good health), 3 (satisfaction with life), 5 (having friends and family), 10 (adjusting to changes), 11 (taking care of oneself), and 18 (being free of chronic diseases). In other words, multidimensionality is a characteristic of the lay concept of aging well involving: physical (2 and 18), psychological (3, 10, 11), and social (5) conditions. These multidimensional items are central to the concept of aging well in all countries. Some problematic methodological issues can be emphasized. First of all, our sample was not representative of the elderly population in our 10 surveyed countries. Second, although our participants come from two continents, all of them belonged to a similar culture, which makes similarities with the existing data from Japan, the country that is culturally the most different from the others, more important. Finally, from an educational point of view, all of our participants were literate, whereas in all surveyed countries, a high percentage of elderly people are illiterate in this cohort, and therefore, it is difficult to generalize our results. In conclusion, according to Matsubayashi et al., there is a gradient of consensus from Japanese in Japan, Japanese in the United States, and white people in the United States, Europeans, and Latin Americans. Also, our results are also coincident with those of Phelan et al. and Matsubayashi et al.; the lay concept of aging well is multidimensional in the mind of elderly adults, supporting those authors who claim against any theoretical reductionism of successful aging. Finally, our third conclusion supports that the scientific concept of successful aging seems to be disseminated around the world, and perhaps this concept has the same meaning around the world. This is important, because the Second International Plan of Action on Aging4 and the World Health Organization5 consider the promotion of active aging supported by research in this field to be a key international objective. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the author and has determined that none of the authors have any financial or any other kind of personal conflicts with this letter. Author Contributions: Rocío Fernández-Ballesteros planned and implemented the study, collected the Spanish data, and wrote the letter. Luis F. García performed all statistical analyses. All the other authors collected the data from their countries. Sponsor's Role: There was no sponsor.