We examined the use of residential services for people with intellectual disabilities in Finland from a regional perspective. Our aims were to investigate how service supply and need, as well as municipal factors, impact the use of residential services and to analyze whether the available information in registers and databases can be effectively utilized in studies of this kind. According to the model based on the register data, after age adjustment the most important factors determining service use were service supply, the prevalence of intellectual disabilities, the municipality's level of urbanization, the number of persons granted long-term care as a percentage of all care recipients, and the percentage of middle-class and managerial households in a given municipality.