cob, light-clay, adobe, compressed earth block, cordwood masonry, timber, earthship, earthbag, bamboo, and stone. What all these methods have in common is that they attempt to radically shortcircuit the extended processing of mainstream industrial materials. In doing so, they present a major challenge to industrialisms consumer values, its view of work, and its concepts of professionalism, bureaucracy and specialization. Natural building also presents a de facto challenge to industrial markets, since much of its labour, materials and energy is deployed completely outside the formal (or cash) economy. It constitutes what Toffler (1980) first called prosumptionthe home-based production that mainstream economics would normally consider simply passive consumption. In this sense, the natural building movement is a logical progression from the owner-builder movement of the seventies, where it was mainly labour which was off the market. The materials of natural building are, almost by definition, indigenousto the region and sometimes even to the building site. For this reason, the natural building movement is much closer to the appropriate technology, traditional and informal building movements of the underdeveloped world. Even without full costs built into market prices, the industrial system produces expensive building materials, which the Third World has neither the resources to support nor the income to afford. While obviously concerned with resource efficiency, the natural building movementmore any other segment of the green building movementis also concerned with community, with creative expression, intrinsic work satisfaction, and with establishing a new spiritual relationship to the built-environment and the Earth. Nowhere else in the literature on building materials is there such treatment of social justice,