The first detailed investigation of the human remains from the Carrowkeel passage tomb complex since their excavation in 1911 has revealed several new and important insights about life, death, and mortuary practice in Neolithic Ireland. Osteological analysis provides the first conclusive proof for the occurrence of dismemberment of the dead at Irish passage tombs, practised contemporarily with cremation as one of a suite of funerary treatments. The research also highlights changes in burial tradition at the complex over the course of the Neolithic. Providing a chronology for these changes allows them to be linked to wider trends in monument construction, which may relate to changes in both land use and climate during the period. Multi-isotope analysis hints at the presence of non-local individuals among the interred and the possible existence of different food sourcing areas at the onset of the later Neolithic period. Preliminary results from ancient DNA sequencing of six individuals from Carrowkeel provide evidence for the genetic ancestry of Irish Neolithic populations, demonstrating their Anatolian origins and links along the Atlantic façade.