To validate a self-administered questionnaire about social and corporal sexual behaviors among adolescents, by school level and gender. The data collection instrument was constructed according to DeVellis and consisted of 26 items. It was used in a prospective longitudinal study conducted in 1994 in Guadalajara, Mexico, among 1243 secondary and high school students. The construct validity of the instrument was established using exploratory factorial analysis, and its reliability using the Cronbach's alpha test. Five factors were obtained in males and an equal number in women, using eigenvalues > 1 and by forcing the best solution. The explained variance was 59.3-70.6%; the factorial weight average was 0.63-0.75, and 13 different factors were selected. The Cronbach's alpha mean was 0.87-0.93 and 16 factors had Cronbach's alpha over 0.70. The instrument has an acceptable validity and reliability for studying the sexual, social, and corporal behaviors in adolescents similar populations.