Objectives: To examine effectiveness of abstinence-until-marriage curriculum on knowledge, beliefs, efficacy, intentions, and behavior. Methods: Nonrandomized control trial involving 2069 middle school students with a 5-month follow-up. Results: Intervention students reported increases in knowledge and abstinence beliefs, but decreases in intentions to have sex and to use condoms. Intervention did not influence sexual initiation or condom use; however, intervention students who had sex during the evaluation period reported fewer sexual episodes and fewer partners than did controls. Conclusions: Abstinence-until-marriage interventions can influence knowledge, beliefs, and intentions, and among sexually experienced students, may reduce the prevalence of casual sex. Reduction in condom use intentions merits further study to determine long-term implications. [ABSTRACT FROM AUTHOR]; Copyright of American Journal of Health Behavior is the property of PNG Publications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)