The papers in this volume provide an exhaustive inventory and description of the most complete sedimentary sequences across the Eocene-Oligocene Boundary (EOB) from all over the world, and present a synthesis of the biotic and chemico-physical events detected at the Eocene-Oligocene transition. The content of the book represents the results achieved by Project no. 174 on ''Geological Events at the Eocene-Oligocene boundary'' of the International Geological Correlation Program, sponsored by UNESCO. The project was carried out over a five year period and has provided a wealth of new and interesting information.