IDS-TILDA is a longitudinal study researching ageing in Ireland among people with an intellectual disability aged 40 and over. This study is the first of its kind in Europe, and the only study able to directly compare the ageing of people with intellectual disability with the general ageing population. The underpinning values of IDS-TILDA are inclusion, choice, empowerment, person centred, the promotion of people with intellectual disability, the promotion of best practice and to make a contribution to the lives of people with intellectual disability.