Background: Adolescent girls in the United States and around the world are at a heightened risk for sexually transmitted diseases (STDs), including human immu nodeficiency virus (HIV). Objective: To determine the efficacy of a skill-based HIV/STD risk-reduction intervention in reducing self-reported unprotected sex ual intercourse among African American and Latino adolescent girls. Design: Rand omized controlled trial with 3-, 6-, and 12-month follow-ups. Setting and Pa rticipants: Sexually experienced African American and Latino adolescent girls re cruited from the adolescent medicine clinic of a children’s hospital serving a low-income inner-city community (N = 682, mean age, 15.5 years); 88.6%were re tained at the 12-month follow-up. Interventions: Three 250-minute interventio ns based on cognitive-behavioral theories and elicitation research: an informat ion-based HIV/STD intervention provided information necessary to practice safer sex; a skillbased HIV/STD intervention provided information and taught skills n ecessary to practice safer sex; or a health-promotion control intervention conc erned with health issues unrelated to sexual behavior. Main Outcome Measures: Pr imary outcome measure was self-reported frequency of unprotected sexual interco urse; secondary outcomes included the frequency of sexual intercoursewhile intox icated, the number of sexual partners, biologically confirmed STDs, and theoreti cal mediator variables, including the intention to use condoms, beliefs about us ing condoms, and condom-use knowledge. Results: No differences between the info rmation intervention and the health control intervention were statistically sign ificant. Skills-intervention participants (mean [SE], 2.27 [0.81]) reported les s unprotected sexual intercourse at the 12-month follow-up than did informatio n-intervention participants (mean [SE], 4.04 [0.80]; P = .03), or health contro l-intervention participants (mean [SE], 5.05 [0.81]; P = .002). At the 12-mont h follow-up, skills-intervention participants (mean [SE], 0.91 [0.05]) reporte d fewer sexual partners (P = .04) compared with health control-intervention par ticipants (mean [SE], 1.04 [0.05]) and were less likely to test positive for STD (mean [SE], 10.5%[2.9%])-than were health control-intervention participants (mean [SE], 18.2%[2.8%]; P = .05). No differences in the frequency of unprote cted sexual intercourse, the number of partners, or the rate of STD were observe d at the 3-or 6-month follow-up between skill-intervention participants and information-intervention or health control-intervention participants. Conclusi on: Skillbased HIV/STD interventions can reduce sexual risk behaviors and STD ra te among African American and Latino adolescent girls in clinic settings. Background: Adolescent girls in the United States and around the world are at a heightened risk for sexually transmitted diseases (STDs), including human immu nodeficiency virus (HIV). Objective: To determine the efficacy of a skill-based HIV / STD risk- Reduction intervention in reducing self-reported unprotected sex ual intercourse among African American and Latino adolescent girls. Design: Rand omized controlled trial with 3-, 6-, and 12-month follow-ups. Setting and Pa rticipants: Sexually experienced African American and Latino adolescent girls re cruited from the adolescent medicine clinic of a children’s hospital serving a low-income inner-city community (N = 682, mean age, 15.5 years); 88.6% were re tained at the 12-month follow-up. : Three 250-minute interventio ns based on cognitive-behavioral theories and elicitation research: an informat ion-based HIV / STD intervention provided information necessary to practice safer sex; a skillbased HIV / STD intervention provided i nformation and taught skills n ecessary to practice safer sex; or a health-promotion control intervention conc erned with health issues unrelated to sexual behavior. Main Outcome Measures: Pr imary outcome measure was self-reported frequency of unprotected sexual interco urse; the frequency of sexual intercoursewhile intox icated, the number of sexual partners, biologically confirmed STDs, and theoreti cal mediator variables, including the intention to use condoms, beliefs about us ing condoms, and condom-use knowledge. r-intervention intervention and the health control intervention were statistically significant. Skills-intervention participants (mean [SE], 2.27 [0.81]) reported les s unprotected sexual intercourse at the 12-month follow-up than did informatio n-intervention participants [SE], 4.04 [0.80]; P = .03), or health contro l -interveners (mean [SE], 5.05 [0.81]; P = .002). At the 12-mont h foll(mean [SE], 0.91 [0.05]) reporte d fewer sexual partners (P = .04) compared with health control-intervention par ticipants (mean [SE], 1.04 [0.05]) and were less likely to test positive for STD (mean [SE], 10.5% [2.9%]) - than were health control-intervention participants (mean [SE], 18.2% [2.8%]; P = .05) in the frequency of unprote cted sexual intercourse, the number of partners, or the rate of STD were observed d at the 3-or 6-month follow-up between skill-intervention participants and information-intervention or health control-intervention participants. Conclusi on: Skillbased HIV / STD interventions can reduce sexual risk behaviors and STD ra te among African American and Latino adolescent girls in clinic settings.