Gender is an important factor in understanding premarital sexual attitudes and behaviors. Many studies indicate that males are more likely to initiate sexual intercourse and have more permissive perceptions about sex than females. Yet few studies have explored possible reasons for these gender differences. With samples of unmarried adolescents in three Asian cities influenced by Confucian cultures, this article investigates the relationship between underlying gender norms and these differences in adolescents' premarital sexual permissiveness (PSP). In a collaborative survey conducted in 2006-2007 in urban and rural areas of Hanoi, Shanghai, and Taipei, 16,554 unmarried participants aged 15-24 years were recruited in the three-City Asian Study of Adolescents and Youth, with 6,204, 6,023, and 4,327 respondents from each city, respectively. All the adolescents were administered face-to-face interviews, coupled with computer-assisted self-interview for sensitive questions. Scales on gender-role attitudes and on PSP for both male and female respondents were developed and applied to our analysis of the data. Multilinear regression was used to analyze the relationship between gender-role attitudes and sexual permissiveness. Male respondents in each city held more permissive attitudes toward premarital sex than did females, with both boys and girls expressing greater permissiveness to male premarital sexual behaviors. Boys also expressed more traditional attitudes to gender roles (condoning greater inequality) than did girls in each city. Adolescents' gender-role attitudes and permissiveness to premarital sex varied considerably across the three cities, with the Vietnamese the most traditional, the Taiwanese the least traditional, and the adolescents in Shanghai in the middle. A negative association between traditional gender roles and PSP was only found among girls in Shanghai and Taipei. In Shanghai, female respondents who held more traditional gender-role attitudes were more likely to exercise a double standard with respect to male as opposed to female premarital sex (odds ratio [OR] = 1.18). This relationship also applied to attitudes of both girls and boys in Taipei (OR = 1.20 and OR = 1.22, respectively). Although with variation across sites, gender differences in PSP and attitudes to gender roles among adolescents were very significant in each of the three Asian cities influenced by Confucian-based values. Traditional gender norms may still be deeply rooted in the three cities, especially among females; while it is important to advocate gender equity in adolescent reproductive health programs, the pathway of traditional gender norms in influencing adolescent reproductive health outcomes must be understood, as must differences and similarities across regions.