Computer science education is widely viewed as a path to empowerment for young people, potentially leading to higher education, careers and development of computational thinking skills. However, few resources exist for people with cognitive disabilities to learn computer science. In this paper, we document our observations of a successful program in which young adults with cognitive disabilities are trained in computing concepts. Through field observations and interviews, we identify instructional strategies used by this group, accessibility challenges encountered by this group and how instructors and students leverage peer learning to support technical education. Our findings lead to guidelines for developing tools and curricula to support young adults with cognitive disabilities in learning computer science.