Several decades of research have identified the contributions of psychosocial influences on adolescent and young adult sexual behavior; however, few studies have examined parental and peer influence and sexual values during the transition from high school to college. The current study tested the influence of sexual values and perceived awareness and caring (PAC), or beliefs about how much parents and peers know and care about students' behavior, on sexual behavior during this transitional period. Using data from a longitudinal study, generalized estimating equations and the generalized linear model were used to examine the associations among sexual values, parental and peer PAC, and sexual behavior, both cross-sectionally and longitudinally. Participants (N = 1,847; 61% female) completed web-based surveys the summer before college matriculation and at the end of the first semester in college. Results indicated that individuals with high levels of both parental and peer PAC engaged in less frequent sexual behaviors and that PAC moderated the effect of sexual values on sexual behaviors. Furthermore, both PAC variables decreased during the transition from high school to college, and high school sexual values, parental PAC, and their interaction predicted the number of sexual partners during the first semester of college. Only sexual values and high school unsafe sexual behaviors predicted unsafe sexual behavior in college. Findings suggest that complex associations exist among perceived awareness and caring, sexual values, and sexual behaviors, and that the transition from high school to college may be an ideal time for safer-sex interventions.