Controversies exist regarding the effects of sex education in the schools and informal sex education obtained from parents, peers, the mass media, and other sources. Similarly, there is widespread interest in premarital sexual behavior, especially its determinants. This study presents several issues reflecting these concerns which have been the subject of much speculation but which have received little attention by researchers. The purpose of this study was to investigate--through the use of respondent reports--how formal and informal sex education influences premarital sexual behavior during college. A national probability sample of 1177 college students was studied using face-to-face interviews with approximately equal numbers of males and females. These interviews, which were conducted for the Institute for Sex Research, included questions about past and present sexual involvement and other attitudinal, behavioral and background variables. Accordingly, the data about sexual behavior and attitudes are based on the interviewees' self-reports. Indices were created which operationalized independent variables such as familial sexual conservatism, exposure to eroticism, perceived sex knowledge, and sexual exposure and assault during childhood and adolescence. Individual items reflecting childhood sex play, masturbation, current religiosity, religiosity while growing up, social class, sources of sex information, sex education in classrooms, and high school and college dating were used. The dependent variable, premarital sociosexual involvement, is a composite measure of incidence and prevalence of premarital heterosexual involvement which meets Guttman scaling criteria. An Automatic Interaction Detector analysis was used to determine the relative influences of reported sexualization variables on premarital sexual behavior. Major findings can be summarized as follows: Heterosexual behavior progresses in stepwise fashion from elementary to advanced levels of involvement, with each level representing a threshold. Reports of current influences and pressures explain more variance in premarital sexual behavior than reports of past informal sexualization influences, which, in turn, explain more variance than reported formal sex-education experiences. Limited success was reported with the use of a four-stage AID analysis which attempted to ascertain whether variables represented in later stages of the sexualization process "mask" the effects of variables in earlier stages and whether a development process can be identified. It may be concluded that these data do not support the belief that exposure to sexuality through formal sex education influences premarital sexual behavior. Informal sex education has significantly more impact on premarital sexual behavior, but there are indications that pressures and experiences confronting young people in a given dating or peer group situation take precedence over all past sexual socialization influences.