Based on census materials collected in England and Wales from 1921 to 1991, this study focuses on gender differences in occupancy rates in hospitals and other mental health facilities in Britain. The results suggest that since 1991, or for the first time in the twentieth century, there are more males than females in residential mental health facilities in Britain. Furthermore, this pattern of association holds for all age groups except those aged 65 years and over. Second, there are currently two distinct subpopulations in mental health facilities—a male group which is predominantly of working age, and a female group, which is predominantly of retirement age. The existence of these two “care” populations will impact significantly on current and future resourcing of mental health services. The policy implications of the research findings are discussed within the context of the debates on the changing relationship between gender and mental health.