The general aim of this thesis is to describe mortality, health and living conditions in an administratively defined county population of people with intellectual disabilities born between 1959 and 1974 (N=213). The living conditions of persons with intellectual disabilities were compared with those of the general population. Moreover, the reports of relatives and staff were compared on the living conditions of people with intellectual disabilities. Information on the living conditions of persons with intellectual disabilities was provided by proxy (relative and staff) questionnaire reports and national welfare statistics conducted by Statistics Sweden (SCB). Medical examination and medical case records were used to obtain data on health and medical services. People with intellectual disabilities lived in the community and took part in numerous common recreational and cultural activities. However, the comparison with the general population indicated clear differences in living conditions, particularly regarding employment and social life. In contrast, surprisingly little variation in living conditions was found in people with intellectual disabilities, despite varying ages and a wide range of level of disabilities. In addition, gender related differences of persons with intellectual disabilities were few when compared with those found in the general population. A wide range of physical and mental health problems were identified in the group with intellectual disabilities. Although a majority of persons with intellectual disabilities had access to a family doctor and attended regular health checks, a number of needs of specialist examinations were identified indicating shortcomings in the quality of health care. Analyses indicated differences in the reports of relatives and staff on living conditions of most domains included in the questionnaire. In general, disagreement was higher on subjective than on objective items. Relative and staff responders contribute dissimilar information that is related to varying viewpoints and different types of information.