Background: Sex education should include social skills, such as those that allow individuals to relate, socialise, and communicate with others, to assist people with intellectual disability (ID) to live life fully in the community. Objectives: We administered and investigated the effects of a program involving 8 interactive sex education sessions that were aimed at improving the social skills of people with ID. Methods: Participants were 17 people with ID and 17 control group participants in Japan. The evaluation was conducted with a questionnaire based on KiSS-18 (Kikuchi's Scale of Social Skills: 18 items; Kikuchi, 2007). Results: The score of KiSS-18 in the experimental group was 55.4 [plus or minus] 12.9 before the administration of the program, as compared to a mean of 61.8 [plus or minus] 13.2 after the program. A significant increase was identified. There was no significant difference between the first and second average score in the control group. Conclusion: The sex education program involving social skills training for people with ID had significant effects. (Contains 3 tables.)