The purposes of this study were to determine whether there were significant differences in knowledge and attitudes among fifth-, ninth- and twelfth-grade students after having been taught a unit on Human Growth, Development and Sexuality and to determine whether there were significant differences between these students and students not receiving the unit. The study attempted to determine at which of the three levels the human sexuality unit was most effective in transmitting knowledge and changing attitude in the area of human sexuality. An attempt was made to determine if there were significant differences between males and females in the knowledge obtained or attitude changes.