This article focuses on the ways in which patterns of marriage and fertility shape older people's involvement in community groups and their support networks. The data are from Australia, Finland, Germany, Israel, Japan, the Netherlands, Spain, the United Kingdom, and the United States. Findings show that childless older adults, regardless of marital status and gender, are equally as likely as parents to be active in the community and in voluntary organizations and to perform volunteer work. Never-married childless women are particularly active socially. Married, childless men are particularly dependent on their wives. In general, childless people are less likely than are parents to have robust network types capable of maintaining independent living without recourse to residential care during conditions of frailty. In some countries, it appears to be marriage rather than parenthood that makes the difference in support networks. (Contains 3 tables and 1 note.)