This study provides an up-to-date re-assessment of the Neolithic burial monuments of Carmarthenshire and Pembrokeshire. The core of the book is an account of every site that has ever been described as a cromlech or chambered tomb; there are 71 of them. These accounts are based on personal visits to the sites or, where they are no longer accessible, on the available antiquarian and archaeological records. New plans and elevations have been prepared for the majority of the mnuments where chamber structures remain. The discussion reviews present knowledge of the Neolithic in South West Wales, and the archaeological evidence recovered from the tombs. The classification of sites with such disturbed remains is viewed critically.