This article discusses the contribution that international comparisons of the health and well-being of older people make. The comparability of the "HRS family" of studies that have been modeled on the U.S. Health and Retirement Study (HRS) is discussed. The Irish Longitudinal Study of Ageing (TILDA) is introduced, and the comparability of TILDA data with respect to the HRS family and other studies is described, along with what TILDA will add to international aging research. Data from the 2010 waves of TILDA, HRS and the English Longitudinal Study of Ageing are used to compare the physical and cognitive health of older Irish adults with that of the U.S. and English populations. The study shows that the physical and cognitive health of older people in Ireland is closer to that of their English counterparts than of those in the United States and that similar health inequalities exist in all three countries.