This book presents the results of cutting-edge research into a newly recognised type of site – Neolithic crannogs – across the Outer Hebrides. It documents underwater and terrestrial excavation at three sites in the Isle of Lewis, as well as extensive new surveys of 30 other crannogs across the island chain. The project explores a wide range of innovative digital methods and scientific techniques, from the use of artificial intelligence and uncrewed aerial vehicles, to photogrammetry, sedimentary DNA, lipid and biomarker analysis. This research helps rewrite our understanding of this critical period of prehistory, and more broadly how we approach these fascinating sites and their rich environments. Crannogs are an evocative category of archaeological site, found widely across Scotland and Ireland. Generally they have been considered to date anywhere between the Late Bronze Age and post-medieval periods. Over 550 ‘archaeological islands’ are recorded in Scotland; the Outer Hebrides represent a particular hotspot, with over 170 recorded sites. The vast majority of these are completely undated, and the notion that all crannogs are likely to have Bronze/Iron Age origins remains unproven. There have been indications for some time that the story of crannogs may extend further back in time than widely imagined. In the late 1980s, the supposedly Iron Age crannog was Eilean Domhnuill, North Uist was shown to have Neolithic origins. It was broadly considered to be an unparalleled oddity until 2012 when a combination of desk- and diver-based work identified a range of Neolithic crannog sites in Lewis associated with extensive assemblages of Neolithic pottery. The Islands of Stone project (2017–2023) was developed to address this clear gap in our knowledge about the origins of these sites. Combining underwater, aerial and ground based survey with excavation, it investigated three islets on the Isle of Lewis in detail. This work confirmed that they were constructed during the Neolithic, and revealed exceptional organic preservation of timber architecture along with highly unusual practices of deposition of material culture into the lochs. Extensive survey of 30 sites across North and South Uist and Benbecula identified a further three Neolithic crannogs, also providing significant insights into 27 others. We now have widespread, compelling evidence for much earlier artificial islet construction and use in the Outer Hebrides, belonging to the first farming communities in the region.Neolithic crannogs represent a new site type for the European Neolithic. The discovery and excavation of the remarkable sites explored here pose fundamental questions about the earliest construction of crannogs, and the nature and extent of Neolithic waterside settlement and ceremony. This book sheds important new light on this most intriguing of site types.