Andrew Beattie and Paul Ehrlich tell us about the millions of species providing ecosystem services that maintain the quality of our air and water and the fertility of the soil, dispose of domestic, industrial, and agricultural waste, and protect crops from pests. The authors also describe how biological diversity opens the way for new medicines, pharmaceuticals, construction materials and designs, and manufactured goods. They point to innovative industries that harness species for the biological repair of damaged landscapes, biological mining, biological pest control, and biomonitoring of the environment. The organisms upon which these activities are founded -- although often microscopic, obscure, or bizarre -- provid