Alcohol consumption, a risk factor for HIV transmission in sub-Saharan Africa, is considered high in Uganda. The study was conducted to determine whether sex-related expectations about the effects of alcohol help explain the association between alcohol use and risky sexual behaviors in a population-based sample of adults in Kampala. A two-stage sampling procedure was used to identify residents in one division of Kampala for a cross-sectional study. Associations between alcohol use (current and higher-risk drinking) and high-risk sexual behaviors (multiple regular partners and casual sex) were tested. Final models included a sex-related alcohol outcome expectancy (AOE) summary score. In age-sex-adjusted models, having multiple regular partners was associated with current drinking (Odds Ratio (OR)=2.76, 95% Confidence Intervals (CI)=1.15, 6.63) and higher-risk drinking (OR=3.35, 95%CI=1.28,8.71). Associations were similar but not statistically significant for having a causal sex partner. Sex-related AOE were associated with both alcohol use and high-risk sexual behavior and attenuated relationships between multiple regular partners and both current drinking (OR=1.94, 95%CI=0.57,6.73) and higher-risk drinking (OR=2.44, 95%CI=0.68,8.80). In this setting sexual behaviors related with alcohol consumption were explained, in part, by sex-related expectations about the effects of alcohol. These expectations could be an important component to target in HIV education campaigns.