Amongst the earliest stone architecture in the world, the Neolithic temples and hypogea of Malta testify to a sophisticated island culture. Explored in the early twentieth century, the subterranean burial temple, the Ħal Saflieni Hypogeum, was cleared of its burials and artefacts without detailed record. Late in the twentieth century, excavation at Xagħra on Gozo rediscovered a second cave cemetery that provides a unique comparison through the investigation of a substantial portion of the buried site using modern scientific techniques. This programme revealed one of the largest prehistoric burial assemblages of human remains yet discovered in the Mediterranean, amounting to some 220,000 bones, together with a rich assemblage of animal bone, figurative sculpture, symbolic artefacts and architectural remains. The detailed factual and interpretative report on this site, supported by fresh scientific data on raw materials, landsnails and environment, isotopes, radiometric dating and statistical analysis, is placed in the broader framework of the domestic and ritual landscape of the Maltese Islands. The result is one of the most comprehensive studies of the incipient complexity of this mature, agricultural, but non-urban, island society so far published.