The other chapters of this thesis are about, successively, the evaluation, production, consumption, recycling and regulation of building materials. This chapter is, in a sense, about all of those dimensions in one chapter because it is about the ultimate alternative, natural building materials. By natural I include the materials used by the many varieties of pre-industrial and vernacular buildingstone, earth, straw, timber, grass, etc. These tend to be derived more directly from the earth, and also more safely and naturally assimilated by the earth at the end of their service lives. But the contemporary natural building movement also encompasses some unusual new building methods that also make the most of plentiful local materials, even if those materials (waste paper, old tires, etc.) are very industrial in origin. Perhaps most interesting is how the movement is combining elements of old and new, manufactured and self-made. It is doing this by combining materials (e.g. straw bale with cob; timber with cordwoodmasonry; rammed earth with tire walls), and by the observation and application of thrifty traditional building principles to new materials, methods and situations. Some of the alternative building methods discussed in this chapter include rammed earth, straw bale,