The marine Eocene-Oligocene transition of 34 million years ago was a critical turning point in Earth’s climatic history, when the warm, high-diversity greenhouse world of the early Eocene ceded to the glacial, icehouse conditions of the early Oligocene. This book surveys the advances in stratigraphic and paleontological research and isotopic analysis made since 1989 in regard to marine deposits around the world. In particular, it summarizes the high-resolution details of the so-called doubthouse interval (roughly 45 to 34 million years ago), which is critical to testing climatic and evolutionary hypotheses about the Eocene deterioration. The authors’ goals are to discuss the latest information concerning climatic and oceanographic change associated with this transition and to examine geographic and taxonomic patterns in biotic turnover that provide clues about where, when, and how fast these environmental changes happened. They address a range of topics, including the tectonic and paleogeographic setting of the Paleogene; specific issues related to the stratigraphy of shelf deposits; advances in recognizing and correlating boundary sections; trends in the expression of climate change; and patterns of faunal and floral turnover. In the process, they produce a valuable synthesis of patterns of change by latitude and environment.