Sex education for individuals with intellectual disabilities is important. However, our knowledge about effective methods for teaching sex education to this population is limited. We report the results of a systematic review identifying methods for sex education programs aimed at individuals with intellectual disabilities. In all, 20 articles were included that met the criteria set in terms of topic--the effectiveness of sex education programs--and population of interest--individuals with intellectual disabilities. In these articles, methods for increasing knowledge and for improving skills and attitudes were reported. However, the studies revealed that generalization of skills to real-life situations was often not achieved. There are indications that the maintenance of knowledge and skills still needs extra attention. Moreover, detailed descriptions of the program materials, program goals, and methods used in the programs were often lacking in the reports. Although there is some evidence for methods that may improve knowledge, attitudes, and skills with regard to sex education aimed at individuals with intellectual disabilities, due to the lack of detailed descriptions provided it is unclear under which conditions these methods work. We therefore suggest that authors provide additional detail about methods in future publications or in online supplements.