Social desirability bias and underreporting of HIV risk behaviors are significant challenges to the accurate evaluation of HIV prevention programs for orphans and vulnerable children (OVC) in sub-Saharan Africa. Valid and reliable HIV risk behavior instruments are critical to address these challenges. We assessed the psychometric properties of two risk behavior measures, the World Aids Foundation Survey (WAF) and the Peer HIV Risk Behavior Screener (PHRBS), administered to 210 OVC in Zambia using Audio Computer Assisted Self-Interviewing. All WAF subscales exhibited good internal reliability (α > .80); only the Sexual Behavior Practices subscale strongly distinguished (P < .01) adolescents who engaged in HIV risk behaviors ("cases") from those who did not ("non-cases"). An 8-item version of the PHRBS, refined using exploratory factor analysis, demonstrated good internal reliability (α = 87), differentiated "cases" from "non-cases" (P < .01), and correlated strongly with the Sexual Behavior Practices subcale (r = .34, P < .01). Results suggest that report of peers' sexual behaviors can serve as a proxy for OVCs' own behavior in contexts where social desirability bias affects reporting.