Purpose: To determine the relationships among sociodemographic factors, constructs of the Information, Motivation, and Behavioral Skills (IMB) model, and sexual risk factors associated with acquisition of sexually transmitted infections (STIs) among women entering recruit training for the U.S. Marine Corps. Methods: Participants/Setting: A total of 2157 (94%) female Marine Corps recruits volunteered to participate in a cognitivebehavioral intervention to decrease STIs and unintended pregnancies. Study Design: This cross-sectional study reflects the baseline self-administered questionnaire that assessed sociodemographic factors (age, race/ethnicity, marital status, location of residence), constructs from the IMB model (e.g., knowledge, attitudes about condoms and sex under the influence of alcohol, perceptions of STI risk and selfefficacy, percent of time that a condom is used), and sexual risk factors (number of all sexual and casual partners, condom use, sex under the influence of alcohol/drugs, and knowledge of whether their partners had a history of STIs and/or had other partners). Outcome Variable: The responses to questions about sexual behavior were compiled into a composite risk index that was constructed to reflect the recruits’ overall level of risk for STIs and unintended pregnancy in the three months prior to recruit training entry. Each measure was scored on a 0-15 point scale, resulting in a 0-75 point risk index score. A two-step hierarchical logistic regression assessed correlates of scoring in the highest quartile of the risk index, with IMB constructs entered first followed by sociodemographic factors. Results: Compared to participants at lower risk, those at highest risk for STIs were significantly more likely to be younger [17-19 vs. 20, odds ratio (OR) 1.35, 95% confidence interval (CI) 1.01-1.82], single (vs. married) [OR 3.24, CI 1.63-6.43], have more knowledge about STIs [OR 1.34, CI 1.07-1.67], have less positive condom attitudes [OR 0.54, CI 0.37-0.79], have perceptions of higher STI risk [OR 11.53, CI 5.98-22.23], agree with statements that sex is more likely/enjoyable under the influence of alcohol [OR 0.40 CI 0.26-0.60], be heavy alcohol users [OR 4.45, CI 2.86-6.91], and drug users (yes vs. no) [OR 1.66, CI 1.03-2.68] prior to recruit training entry. Conclusions: Despite having high levels of knowledge and perceptions of higher STI risk, this study suggests the need for ongoing intensive behavioral interventions that emphasize the importance of using barrier methods of contraception to prevent STIs as well as the significance of alcohol