This paper examines the extent of mental ill-health and probable depression among older people in long-term care. It presents selected findings from a study in Greater Belfast, Northern Ireland, that compared the quality of life, autonomy and mental health of older people living in nursing and residential homes with those of older people living in private households who were receiving domiciliary care. Structured interviews were conducted with 214 residents in institutions and 44 older people receiving domiciliary care. The study found that those in private households were more severely physically-impaired and had a higher level of mental ill-health than the residents of institutional homes. It is suggested, however, that the mental ill-health effects were associated less with physical impairments than with the restrictions placed on the older person's decisional autonomy, and that long-term care environments that constrain the older person's autonomy contribute to the development of depression. Although the UK National Service Framework for Older People specified that those with depression should be given treatment and support, priority should also be given to preventing the depression associated with living in long-term care settings.