Adults with intellectual disabilities have high rates of physical inactivity and related chronic diseases. Researchers have called for an increase in the development and evaluation of health education programs adapted to the unique needs of this population. Formative and process evaluation strategies were applied to develop a physical activity education program. The first phase of formative evaluation included a comprehensive literature review to select educational strategies and curriculum content. The theory of planned behavior was selected as a guiding framework, and meetings with stakeholders were held to assess feasibility. The second phase of formative evaluation included an assessment of materials by an expert panel and the priority population, and pilot testing. Next, field testing was implemented, followed by process evaluation and an assessment of implementation fidelity. The final curriculum was developed as a result of the completion of the aforementioned steps and led to a successful physical activity intervention.