Objectives: To identify available literature on the impact of built environments on health, behavior, and quality of life of individuals with intellectual disabilities in long-term care. Additionally, we aimed to map the available literature, (re)frame the overall research situation in this area, and formulate recommendations. Background: Long-term care facilities in the Netherlands are planned without using knowledge from research regarding evidence-based design because it is unclear what evidence is available about the impact of long-term care built environments on individuals with intellectual disabilities receiving 24/7 care. Methods: Twelve scientific databases were searched for keyword combinations. After systematically screening 3,095 documents, 276 were included in the analysis. Results: There is an underrepresentation of research and publications in intellectual disabilities, compared to other user groups living in long-term care facilities. A total of 26 design components were found in all groups; as for intellectual disabilities, research was available on only seven of them. Community care, home-likeness, and variety seem to have a positive effect on health, behavior, and quality of life. There are conflicting results regarding the effects of house size. Conclusions: Although individuals with intellectual disabilities live in long-term care facilities, sometimes for life, little research has been conducted on the impact of the built environment on them. In the future, more empirical research should be conducted, addressing all aspects of quality of life and specific design components, with hypotheses based on needs assessments and the use of good research designs. This requires an investment of time and funding.

development of treatment programmes, provide staff training, influence legislation and regulations, and carry out scientific research about the population and the effects of treatment.The five organisations of De Borg offer temporary treatment. Clients come in from mental health care institutions, institutions for the mentally disabled and from prisons, and after treatment they leave, most often to a lower care institution for the mentally disabled. Together, De Borg institutions provide 224 beds for inpatient treatment together with outpatient treatment for approximately 800 clients. These facilities, however, were previously all low-secure, except the TBS units of Hoeve Boschoord, which were high security. Until recently, there were no medium secure treatment facilities for people with learning disabilities, but now they are in development: there will be 120 new forensic De Borg institutionsIn the Netherlands, there are different facilities for the treatment and care of mentally disabled people. There are 'ordinary' care institutions, where people live and work; mental health care institutions that provide treatment; and there are specialised wards, which have special treatment units for people with learning disabilities and severe challenging behaviour.Five institutions with special treatment units for people with learning disabilities are united in a collaboration, called De Borg. These institutions are Trajectum-Hoeve Boschoord, Trajectum-Hanzeborg, Dichterbij, Altrecht/Wier and Ipse de Bruggen. These five institutions have different backgrounds: one is a TBS facility 1 , one is a facility for mental health care and three are institutions for mentally disabled people. The purpose of De Borg is to facilitate the