A new book on marine biodiversity has been released by the National Research Council’s (NRC) Ocean Studies Board and Board on Biology. Produced by the NRC’s Committee on Biological Diversity in Marine Systems (co-chaired by Cheryl Ann Butman and James T. Carlton), the book’s premise is that the diversity of marine life—at genetic, species and ecosystem levels—is being dramatically affected by human activity. The book identifies fisheries operations, chemical pollution, and eutrophication, alteration of physical habitat, and exotic species invasions as primary drivers of diversity change in marine systems. Critical to finding effective solutions to these and other issues, the report argues, is expanding the understanding of patterns and processes that regulate biological diversity in the sea. The book presents an outline of the current state of knowledge in this area, and then presents potential areas for new discoveries at genetic, species and community levels. It highlights critical gaps in knowledge and expertise, emphasizing the current and potential future costs of declines in the science of systematics, and the need to incorporate support for systematics in oceanographic and ecological research agendas. To meet current and future needs, Understanding Marine Biodiversity proposes a national research agenda to attain a new level of understanding of patterns, processes and changes in biodiversity. The agenda argues for a fundamental change in approaches to studying the ocean, with emphasis on regional-scale research across a broad range of spatial and temporal scales, enhancements in interfaces between taxonomy and ecology, increased cooperative research programs linking ecologists and oceanographers, and utilization of newly available analytical and sampling techniques. This NRC study was funded by the National Science Foundation, Department of Defense/Office of Naval Research, Department of Commerce/National Oceanic and Atmospheric Administration, Department of Energy, and Department of the Interior/National Biological Service all of whom have interests and/or mandates involving marine biodiversity. For more information see J.T. Carlton and C.A. Butman (1995), Oceanus 38(2): 4-8.