Vitamin D insufficiency has been associated with adverse health consequences, principally increased falls, osteoporosis, and fractures. Associations have also been proposed between vitamin D insufficiency and diseases of the immune system, cancer, psychiatric disease, respiratory disease, cardiovascular disease and abnormalities of glucose metabolism. For a number of reasons, vitamin D insufficiency is relatively common in people with intellectual disability (ID). This article serves as a practical guide for clinicians, family members and support workers who care for people with ID. It has been prepared by a Working Party consisting of Australian clinicians and researchers with an interest in the care of people with ID (and endorsed by the Australian Association of Developmental Disability Medicine). The Working Party reviewed the limited literature which specifically pertains to vitamin D and ID, as well as the large body of literature pertaining to vitamin D in general, especially in the elderly. (Contains 1 table.)