The purpose of this study was to examine factors influencing attitudes toward sexual activity among early adolescents in Japan. A total of 1,551 students aged 12 to 14 years at 4 junior high schools were divided into either a conservative or liberal group. Results of chi-square tests showed that the liberal group had higher percentages of students with drinking, smoking, and sexual activity than the conservative group. The liberal group also had more dating partners and friends with sexual experiences than the conservative group. Unpaired "t" test indicated that the liberal group rated lower than the conservative group in talking to their parents about life and AIDS and teachers listening to their opinions. Furthermore, a multiple regression analysis showed that smoking, experience with sex, talking to parents about AIDS, teachers listening to participants' opinion, older dating partners, and friends with sexual experiences were all significant predictors of attitude toward sexual activity. (Contains 3 tables.)