Individuals with high body mass index (BMI), negative body image, and unhealthy weight control behaviors may be more likely to engage in high-risk sexual behaviors than others. Researchers have not fully investigated these relationships in a sample of college students. The authors collected data regarding several weight-related issues and high-risk sexual behaviors (response rate = 39%) from 1,168 college students. Over half reported at least 1 high-risk sexual behavior. After the authors controlled for several demographic characteristics, they found that higher BMIs were associated with increased odds of having a casual sexual partner (odds ratio [OR] = 2.70) and being intoxicated at last intercourse (OR = 2.25). Among women, unhealthy weight control behaviors were associated with having a casual partner (OR = 2.12), using no or unreliable contraception (OR = 1.98), and being intoxicated at last intercourse (OR = 2.31). Weight-related issues were not associated with sexual behaviors among college men. The authors describe their findings within two health behavior frameworks, and they discuss implications for research and health education. (Contains 1 note.)