PURPOSE:To identify factors that are associated with condom use to aid in the understanding of how to change the behavior of those young people who have sex without using condoms. METHODS:The article reports data from 932 sexually active grade 10-12 students from a sample of 72 public secondary schools in seven Australian states and territories. The data were collected using a cross-sectional, self-report questionnaire. RESULTS:Boys were more likely than girls to report that a condom was used the last time they had sex. For boys and girls, communication with a partner about avoiding infection with HIV/STDs, the belief that more peers use condoms, and a higher perceived risk of becoming infected with HIV/STDs were associated with using a condom, as was lower knowledge of STDs. The use of oral contraception and the unavailability of condoms were reported by the students as prominent reasons for non-use of condoms. Number of sexual partners in the past year and type of relationship with partner on the most recent occasion were not associated with condom use. CONCLUSIONS:Adolescents are more concerned with unwanted pregnancy than with disease prevention. School students more at risk are not more likely to take the necessary precautions to protect themselves from HIV/STDs.