This study is a qualitative study designed to examine effectiveness of two sex education programs for increasing sexual knowledge and positive feelings of people with intellectual disability. Sexual knowledge, experiences and feelings of six adolescent and adult men were assessed using the Sexuality Knowledge, Experience, Feelings and Needs Scale for People with Intellectual Disability (Sex Ken-ID), pier to, and at the completion of sex education. The sex education programs were relatively comprehensive, involving 6-10 sessions of sex education in a community health setting. The results of the study demonstrated that there were minimal increases in the sexual knowledge of participants at the end of the programs. These changes were limited mainly to improvements in knowledge of friendship, contraception, pregnancy, sexual interaction and social skills. Low levels of knowledge about masturbation and menstruation remained essentially unchanged. Participants had particular difficulty expressing their feelings about sexuality. After sex education, more positive feelings were expressed in relation to female friendships and hugging someone of the opposite sex. However, the negative feelings of some participants towards girlfriends, masturbation, oral-genital sex and sexual intercourse remained. Following sex education, more negative feelings developed about marriage having children and being present during childbirth. The implications of these findings are discussed in relation to the future design of sex education programs and the need for parental education regarding the sexuality of their children.