Purpose: To examine the contents and characteristics of seniors' online communities and to explore their potential benefits to older adults. Design and Methods: Quantitative content analysis of a full year's data from 14 leading online communities using a novel computerized system. The overall database included 686,283 messages. Results: There was a constant increase in the daily activity level during the research period. Content analysis identified 13 main subjects discussed in the communities, including (in descending order) "Fun on line," "Retirement," "Family," "Health," "Work and Study," "Recreation" "Finance," "Religion and Spirituality," "Technology," "Aging," "Civic and Social," "Shopping," and "Travels." The overall tone was somewhat more positive than negative. Implications: The findings suggest that the utilities of Information and Communications Technologies for older adults that were identified in previous research are valid for seniors' online communities as well. However, the findings suggest several other possible benefits, which may be available only to online communities. The communities may provide social support, contribute to self-preservation, and serve as an opportunity for self-discovery and growth. Because they offer both leisure activity and an expanded social network, it is suggested that active participation in the communities may contribute to the well-being of older adults. Directions for future research and applied implications are further discussed.