"The book before you...carries the urgent warning that we are rapidly altering and destroying the environments that have fostered the diversity of life forms for more than a billion years." With those words, Edward O. Wilson opened the landmark volume Biodiversity (National Academy Press, 1988). Despite this and other such alarms, species continue to vanish at a rapid rate, taking with them their genetic legacy and potential benefits. Many disappear before they can even be identified. Biodiversity II is a renewed call for urgency. This volume updates readers on how much we already know and how much remains to be identified scientifically. It explores new strategies for quantifying, understanding, and protecting biodiversity, including: New approaches to the integration of electronic data, including a proposal for a U.S. National Biodiversity Information Center. Application of techniques developed in the human genome project to species identification and classification. The Gap Analysis Program of the National Biological Survey, which uses layered satellite, climatic, and biological data to assess distribution and better manage biodiversity. The significant contribution of museum collections to identifying and categorizing species, which is essential for understanding ecological function and for targeting organisms and regions at risk. The book describes our growing understanding of how megacenters of diversity (e.g., rainforest insects, coral reefs) are formed, maintained, and lost; what can be learned from mounting bird extinctions; and how conservation efforts for neotropical primates have fared. It also explores ecosystem restoration, sustainable development, and agricultural impact. Biodiversity II reinforces the idea that the conservation of our biological resources is within reach as long as we pool resources; better coordinate the efforts of existing institutionsâ€"museums, universities, and government agenciesâ€"already dedicated to this goal; and enhance support for research, collections, and training. This volume will be important to environmentalists, biologists, ecologists, educators, students, and concerned individuals.