Background. Evidence suggests that adolescent HIV/AIDS prevention intervention has been substantially effective for preventing HIV/AIDS risk-taking behavior. However, it is not clear what specific variables related to program design and implementations have the strongest effect. Purpose. The purposes of this study were to (1) examine whether adolescent HIV/AIDS prevention intervention programs designed to change knowledge, attitudes, beliefs, self-efficacy, and behaviors have been effective and (2) to determine the relationship between program design and implementation elements and outcomes. Method. A meta-analysis was conducted to evaluate the status of these programs. A systematic review of 8 computerized databases, hand searching of 6 journals, and reference lists were undertaken for primary studies published from 1990 to 2002. To be included in the meta-analysis, primary studies had to have: (1) an experimental design, (2) the intervention designed to affect HIV/AIDS risk-taking behaviors targeting adolescent, and (3) outcome data along with details sufficient for calculation of effect size. Data on demographic characteristics of participants, intervention characteristics, methodological considerations, and information necessary for calculation of effect size were extracted independently by 3 reviewers to assess inter-rater reliability. Effect sizes and homogeneity of variance measures were calculated. A number of potential moderators then were examined. Result. A total of 28 studies met the inclusion criteria. The effect sizes for all outcomes were statistically significant. However, most of the effect sizes were small, except for knowledge. Taken collectively, the largest mean effect size is for knowledge (ES = .58, 95%CI = .42 to .72), followed by attitudes toward condoms (ES = .29, 95%CI = .14 to .43), condom use (ES = .28, 95%CI = .14 to .41),attitudes toward AIDS (ES = .26, 95%CI = .11 to .41), self-efficacy (ES = .22, 95%CI = .12 to .31), beliefs regarding condoms (ES = .16, 95%CI = .41 to .31), and beliefs regarding AIDS (ES = .12, 95%CI = .003 to .24). Participant's gender and ethnicity, setting, interventionist, and number of sessions were typical moderators explaining the results. Conclusion. The findings of this study provide state of science information that could enable policy makers to identify the overall effectiveness of these programs and can provide program designers to improve HIV/AIDS prevention programs information. This can help reduce the spread of HIV/AIDS among young people.