Some studies conducted in developing countries indicate that unprotected sexual behavior among unmarried young people is on the rise. Risk-taking, a natural part of growing, in particular unprotected sexual activities are more hazardous because of the prevailing HIV/AIDS pandemic and other associated Reproductive health risks. The main objectives of this study was to explore the level and extent of sexual-behavior among unmarried, youth students and the correlates of that behavior. A cross-section study of sexual experiences and their correlates among 572 Jimma University never-married, youth, students was conducted in April, 2002. Study subjects were selected by stratified, Non proportionate sampling technique using their faculty as a strata and one-batch (class) per department as a sample unit. A total of 9 classes were selected from all departments of the faculties by a simple random sampling technique. Data was collected using a pilot-tested, structured, self-administered questionnaire that comprises; PERSONAL, FAMILIAL and INTERMEDIATE Variables (as Independent) and questions that seeks about student’s sexual-behavior (Dependent). In this study sexual behavior is seen as two variables; Any sexual-experiences and sexual intercourse. The collected data entered to a computer, processed & analysed using statistical package for social sciences (SPSS) for window version 11.0. Chi-square (x2) test were employed to assess the significance of association between student’s sexual behavior & each independent variables and a multivariant logistic regression analysis was used to quantity and compare the likelihood of student’s sexual behavior with the categories of selected independent variables. Out of the total respondents 468 (81.8%) were males & 104 (18.2%) were females; of which 195 (41.7%) males and 33 (31.7%) females had had any sexual experiences and 155 (31.1%) males and 18 (17.3%) females admitted that they have had sexual-intercourse in the past. Mean age at first coitus were 18.1 years with an age range of 10-24 years. Furthermore, among those who had sexual-intercourse 123 (71.7%) had not regular sexual partners but only 80 (46.2%) of them use condom consistently, though there was a significant gender differences. Among the presumed independent variables that can have an influence on student’s sexual-behavior, age and gender (personal) and all intermediate variables had a significant effect while the familial level variables showed no significant association with the student’s sexual behavior. The strongest predictor of student’s sexual-behavior were their attitude towards premarital sex followed by their level of social interaction and exposure to erotic materials. Traditional norms and the role of the family are losing importance in governing young people’s sexual-behavior. While the health sector may be best qualified, the development of broad sexual and reproductive health (RH) agenda for the young people needs an active involvement of the Family-school-society nexus in addressing such issues.