The Island of Ireland’s death literacy has been explored and understood through my PhD. With an ever-increasing ageing population and increased strain on palliative and end-of-life care services, such research is vital. To address such demands, various public health approaches to palliative care have been devised across the island of Ireland. However, with the lack of an accepted outcome measure, their effectiveness was largely uncertain. This PhD adapted a tool to measure death literacy (Death Literacy Index, DLI) across the island of Ireland. Using cognitive interviews with a think-aloud methodology, the Death Literacy Index-Island of Ireland (DLI-IRE) was developed. The DLI-IRE was administered through a population survey and psychometrically validated. Population-level benchmarks were calculated, and predictors of death literacy were explored. An online workshop with death literacy experts across the island, produced a Theory of Change model and five priority recommendations for enhancing death literacy in communities across the island of Ireland.  This PhD research provides the island of Ireland with its first culturally validated tool to assess death literacy and to evaluate and improve the provision and quality of palliative and end of life care services.