Background When sexual partners have risky context characteristics (i.e., partner drinking alcohol within two hours before sex, ≥ 3 age discordant, or met in public), adolescents are particularly vulnerable to having unprotected sex and acquiring sexually transmitted diseases. Based on social cognitive theory, we assessed the influence of adolescents’ alcohol use; their friends’ ages and alcohol use; and parental monitoring on adolescent sexual partner selection to identify potent predictive factors.

Methods Data were from an urban cohort of youth participating in the Project Northland Chicago group-randomised, alcohol preventive intervention trial. We used ordinal logistic regression to analyse the predictive effect of 8^th grade self, peers, and parents factors on a sexual partner context risk score of 0 to 3 with 1 point for each risk characteristic of 17–18 year old adolescents’ most recent sex partner. We adjusted analyses for sexual partner relationship characteristics (casual or unexpected).

Results Women were more likely to choose risky context partners at ages 17–18 years old if in 8^th grade they had older friends [Odds Ratio (OR) = 1.5, 95% Confidence Interval (CI) = 1.1 to 2.1] or reported risky alcohol use behaviours (OR = 1.6, 95% CI = 1.2 to 1.9). Men were more likely to choose risky context partners at ages 17–18 years old if in 8^th grade their friends were drinking alcohol (OR = 1.3, 95% CI = 1.0 to 1.7). Parental monitoring did not influence partner selection.

Conclusions Peers and alcohol use influence adolescents’ selection of risky context partners. For alcohol, self-use appears more important among women, and friends’ use appears more important among men. Interventions to reduce sexual risk-taking and risky partner selection among adolescents should target friends and alcohol use.