The HIV/AIDS epidemic is disproportionately impacting young African Americans. Efforts to understand and address risk factors for unprotected sex in this population are critical in improving prevention efforts. Situational risk factors, such as relationship type and substance use before sex, are in need of further study. This study explored how established cognitive predictors of risky sexual behavior moderated the association between situational factors and unprotected sex among low-income, African American adolescents. The largest main effect on the number of unprotected sex acts was classifying the relationship as serious (event rate ratio = 10.18); other significant main effects were alcohol use before sex, participant age, behavioral skills, and level of motivation. HIV information moderated the effect of partner age difference, motivation moderated the effects of partner age difference and drug use before sex, and behavioral skills moderated the effects of alcohol and drug use before sex. This novel, partnership-level approach provides insight into the complex interactions of situational and cognitive factors in sexual risk taking.