The species richness seen in the living molluscan fauna of the East Coast of the United States is due to its composite nature, containing faunal elements from three contiguous molluscan provinces. These include:the southern warm water Carolinian Molluscan Province (Cape Hatteras, North Carolina to Palm Beach, Florida)the central temperate water Virginian Molluscan Province (Cape Cod, Massachusetts to Cape Hatteras, North Carolina)the northern cold water Acadian Molluscan Province (Labrador, Canada to Cape Cod, Massachusetts). Each of these provinces has been found to house a large component of endemic species, many illustrated for the first time in this book. Detailed descriptions are given of the predecessor faunas that are contained in the Miocene, Pliocene, and Pleistocene fossil beds of eastern North America. Hundreds of extinct species from these Neogene fossil beds are illustrated in separate chapters, describing the marine ecosystems and molluscan faunas that lived during these times. The living and fossil molluscan faunas from the entire coast are illustrated on 128 plates, showing some of the most interesting and beautiful shells that ever evolved anywhere in the world’s oceans. For the first time in any book on American shells, the most prevalent mollusk-bearing ecosystems of the East Coast are described and their resident molluscan faunas discussed in detail. This overview of the biodiversity of the coastal faunas can be used as a baseline for any future biological surveys, establishing the composition of the faunas that are now being impacted by global climate changes and higher marine temperatures. Over the past 25 million years, the East Coast has been subject to periodic ecological collapses, triggered by rapid and severe changes in the local marine environments. As shown here, most of these catastrophes have been caused by extraterrestrial events, such as asteroid impacts and the dimming of the sun by interstellar dust clouds. The resulting climatic degeneration decimated the shallow coastal marine ecosystems, especially in the southern part of the region. These extraterrestrial influences are correlated with the abrupt changes seen in the Neogene fossil record, and are outlined on the numerous charts, diagrams, and maps throughout the book. The book is the ideal companion to “Molluscan Faunas of the Gulf of Mexico: Endemism in North America’s Inland Sea” (Petuch and Berschauer, 2025).