In order to answer important questions about ecosystems and biodiversity, scientists can look to the past geological record—which includes fossils, sediment and ice cores, and tree rings. Because of recent advances in earth scientists'' ability to analyze biological and environmental information from geological data, the National Science Foundation and the U.S. Geological Survey asked a National Research Council (NRC) committee to assess the scientific opportunities provided by the geologic record and recommend how scientists can take advantage of these opportunities for the nation''s benefit. The committee identified three initiatives for future research to be developed over the next decade: (1) use the geological record as a "natural laboratory" to explore changes in living things under a range of past conditions, (2) use the record to better predict the response of biological systems to climate change, and (3) use geologic information to evaluate the effects of human and non-human factors on ecosystems. The committee also offered suggestions for improving the field through better training, improved databases, and additional funding.