Increases in knowledge following a course of sex education for people with intellectual disabilities.

Demello et al. (1992) ran a nine-month sex-education class for adults with intellectual disabilities. They compared the group to similar adults who got no lessons.

Classes met regularly and covered body parts, consent, and safe sex. The team tested everyone's knowledge before, after, and again later.

Adults who took the course scored much higher on sex-knowledge tests. The gains stayed strong months after the last class.

The no-lesson group showed no change. Systematic teaching worked and the facts stuck.

Lancioni et al. (2009) shortened the idea to ten weeks and taught one-to-one. Their adults also learned and kept the skills, showing the core finding holds in tighter doses.

Rojahn et al. (2012) pushed it further: a single computer lesson gave women with ID the same big knowledge jump. Three very different lengths—nine months, ten weeks, one session—all produced large gains, so success is about clear teaching, not clock hours.

Pettingell et al. (2022) swept up 42 studies, including the 1992 paper, and found most work still only tests knowledge, not real-life use. The field keeps copying the 1992 knowledge win but still needs tools for attitudes and safety skills.

You can teach sex ed to adults with ID and they will learn it. Start with a clear scope, break content into small chunks, and check understanding often. Whether you run a semester course, brief BST sessions, or a tablet module, keep the language plain and the examples concrete. Track data so you can show families and funders that knowledge goes up and stays up.