Background: Primary family carers of adults with profound intellectual and multiple disabilities (PIMD) experience a range of considerable demands. Method: A census survey was conducted in a city of Taiwan; 796 family carers of adults (aged 18 or older) diagnosed with intellectual disability and/or with multiple disabilities living with the family completed interviews. Results: Adults with PIMD made up 9.5% of this group (n = 76). Nonparametric analyses showed that health status, formal social support, and quality of life (QoL; physical domain score) of carers of adults with PIMD were significantly lower than their counterparts (i.e., carers of adults with less severe disability), and that these variables were significantly associated with carer educational level, employment status, family income, and social networks. Conclusions: Interventions need to include the creation of a supportive environment for adults with PIMD and their lifelong family carers, particularly those who are more socially disadvantaged. (Contains 3 notes and 2 tables.)