Men who have sex with men (MSM) throughout the world are at high-risk of HIV acquisition and transmission. Although individual behavior remains a central feature of HIV prevention efforts in sub-Saharan Africa and beyond, contextual factors likely influence behavioral risk. We identify contextual factors at the individual, dyadic (within the partnership), and extra-dyadic (relationships external to the focal dyad) levels that are associated with increased rates of unprotected anal intercourse with a given male partner among MSM in Soweto, South Africa. Drawing on data from The Soweto Men's Study, multilevel models were applied to 758 partnerships nested within 377 MSM respondents. Independent of overall sexual engagement, dyadic (e.g. description of partner as 'regular'), psychosocial (e.g. experiences of homonegativity), and sociocultural (e.g. income) contextual factors were significant predictors of differential 6-month rates of UAI with a given partner. By contrast, sexual partnerships outside of the focal sexual pair were not significantly related to UAI rates within the focal pair. Our findings support the need for continuing to understand and intervene on partner-level, psychosocial, and sociocultural dimensions of sexual behavior and sexual risk among MSM in Soweto.