The purposes of this study were to assess sexual behavior and condom use among Chinese college students, and to explore social-environmental and social-cognitive determinants associated with risky sexual behaviors within this population. A survey was conducted among 19,123 Chinese college students recruited through stratified cluster sampling. About 9% of the students reported having had sex (male=13.3%, female=5.0%, OR=2.918), 3.6% had multiple sexual partners (male=5.7%, female=1.6%, OR=3.624), and 0.9% had commercialized sex (male=1.6%, female=0.3%, OR=6.169). Only 24.8% of sexually active students had used a condom for every sexual encounter, and there was no significant difference in condom use between male students and female students. Logistic regression showed that sex (female, OR=0.769), age (older, OR=1.263), exposure to pornographic information (higher, OR=1.751), drinking (intoxication, OR=1.437), and smoking (OR=2.123-5.112) were all determinants of sexual behaviors. Path analysis showed that exposure to pornographic information, level of consumption, and sex education were important social-environmental factors of condom use. Condom use was more common among those who had greater HIV/AIDS knowledge, attitudes toward high-risk behavior, self-efficacy, and intent to use a condom. Intentions were the most important and direct factor influencing condom use. The study concluded that college students are vulnerable to sexually transmitted diseases - including HIV/AIDS infection - through sexual contact. Therefore, future HIV/AIDS prevention and safer sex interventions should focus on self-protection skills and target behavior change.