Cold-water corals form reef structures in continental margin and seamount settings world-wide, making them more wide-spread and abundant than shallow-water reefs. Their role in these ecosystems is no less important than the influence that shallow-water coral reefs have on tropical systems. They create habitat structure, host endemic species, enhance elemental cycling, alter current flow, sequester carbon, and provide many other ecosystem services that we are just beginning to understand. The rapidly evolving state of knowledge of cold-water and deep-sea coral reefs has not been compiled in over 10 years. This volume synthesizes recent and historical information, reveals new findings from reefs that have been discovered only recently, and presents key avenues for future research. We are on the cusp of understanding the critical role that cold-water coral reefs play in the world’s oceans, and this book lays the foundation on which this knowledge will be built in the future.