College women are at more risk in terms of sexual behavior than male students. This study was carried out to determine the effect of the transtheoretical model-based Healthy Youth Program on college women's sexual health knowledge and behaviors. The sample of the study, which was conducted with a one-group pretest-posttest quasi-experimental design, consisted of 207 first-year college women. It was determined that the Healthy Youth Program was effective in improving the sexual health knowledge and behaviors of college women. It can be used as a guide in sexual health education in colleges.