Many families provide lifelong support to their relative with an intellectual disability. However, relatively little information is available for national populations on the characteristics of the people for whom these families care and the supports they receive or need. A database of all persons in receipt of intellectual disability services has been operating in the Republic of Ireland since 1995 and records details of those living with family carers. In Northern Ireland, regional databases provide similar information. Using both sources, data were obtained on over 12,500 people living with family carers; half of whom lived with two parents, around 30% with a lone parent, and just under 20% with another relative. More people in Northern Ireland were identified as living with family carers, which was attributed mainly to less available residential alternatives. Only a minority of carers received respite breaks and domiciliary supports although higher proportions required them. The authors conclude that family care arrangements have received relatively little attention within government policy making, and hence service provision has been largely reactive. Future research should focus on the changing needs of carers over time and how they can be better supported in their role.