the irish longitudinal study on ageing (tilda) is a nationally representative longitudinal study of the population of ireland aged 50 and above. tilda aims to understand how the health, social and financial circumstances of the older irish population and how these factors interact. the study is led by trinity college dublin (tcd) in collaboration with a majority of the other principal academic institutions in ireland. a wide range of experts from many disciplines have been involved from the outset in the development and execution of this study.