A number of authors have identified multiple sexual partnerships by both men and women, particularlyoverlapping or concurrent partnerships, to lie at the root of the HIV/AIDS epidemic in sub-SaharanAfrica. In this paper we examine the influence of social and cultural context in men‘s and women‘sinvolvement in multiple sexual partnerships in sub-Saharan Africa, above and beyond the effects ofindividual characteristics. The data used in this study come from population-based sample surveys(Demographic and Health Surveys and AIDS Indicator Surveys) that were conducted in mid 2000s in 20countries in sub-Saharan Africa. Our analytical approach features multilevel modeling, placing particularemphasis on country and community (ethnic group) characteristics that are likely to determineinvolvement in risky sexual behavior. The findings provide support to the ecological argument that healthbehaviors are shaped and determined by societal conditions, in addition to the effects of individual andhousehold characteristics. Involvement with multiple sex partners is significantly most likely among menand women who live in societies in which early sexual debut or polygyny is most prevalent. The effects ofindividual characteristics suggest that increases in human and social capital skills are not necessarilyassociated with socially conservative and healthful sexual behaviors in sub-Saharan Africa. Men andwomen who are most likely to have multiple sex partners in the region are those who have the individual attributes that bring to them more rights and decision-making autonomy but not necessarily more financialand social resources: young age, urban residence, education, media exposure, and working for cash andaway from home. Findings from this study suggest a number of opportunities for more effective policyand programmatic responses to curb the spread of the HIV epidemic in sub-Saharan Africa. In particular,the results argue strongly for behavior change and partner reduction efforts within communities in whichhigher-risk behaviors such as multiple concurrent partnerships are normalized and most prevalent