This research addresses the issue of HIV/AIDS education for Year 10 students. The purpose of this study was twofold: to provide baseline data on students' knowledge, beliefs, and attitudes about HIV and AIDS (Phase 1), and to evaluate the effect of an education intervention on possible determinants of behaviour (Phase 2). The study drew a non- random convenience sample of 269 students from two senior high schools in Perth, Western Australia. One school received the education intervention; the other was used as the control group. Phase 1: A questionnaire-was administered to gather baseline data on AIDS knowledge, attitudes, perceived risk, and intention to change risk behaviours. Students were also asked to Identify sources of HIV/ AIDS information. Results revealed that students knew most about the prevention of HIV/AIDS, and least about its transmission. Phase 2: A pre-test was administered to both groups to gather data on existing AIDS knowledge, attitudes, perceived risk, and intention to change risk behaviours. The data gathered in Phase 1 also served as the pre- test data in Phase 2. Following the pre-test, students in the experimental group were given an HIV/AIDS education program, and tested immediately following its completion. Six weeks later, both groups were evaluated using a questionnaire identical to the pre- test and intervention test, to allow comparison of data between the groups, and to evaluate the effect of the intervention. To allow for pre-test differences, post- test scores were subtracted from pre-test scores. Using these difference scores, t-test analyses were conducted to test the hypotheses. Results indicated support for hypotheses investigating the effect of the intervention on adolescents' knowledge about HIV/AIDS, perceived severity, and perceived pressures. However, differences in responses relating to knowledge of prevention, preventive intentions, and perceived barriers, were not statistically significant. At post- test, the experimental group maintained knowledge levels, felt less threatened and less susceptible to AIDS, acknowledged fewer pressures, and were less inclined to practice preventive health behaviours. Study findings have implications for nursing practice, health education, planning, and research.