This chapter reviews the morphodynamics of open-ocean barrier systems, synthesizing classic studies, current scientific knowledge, and future research directions regarding 14 barrier provinces worldwide. Within a coastal tectonic framework, it addresses: (1) Amero-trailing-edge coasts (USA’s New England coast, Mid-Atlantic Bight coast, North Carolina Outer Banks, Georgia Bight coast, Florida Atlantic coast; Brazil’s Santa Catarina coast; Europe’s German Bight coast; Australia’s southern and western coasts); (2) marginal-sea coasts (USA’s Florida Gulf Coast; Gulf Coast of Louisiana, Mississippi, and Alabama; Texas Gulf Coast; Australia’s eastern coast); and (3) collision coasts (USA’s Alaskan Pacific coast, Japan’s and New Zealand’s coasts). This chapter also provides a glossary, important conclusions, specific recommendations regarding future coastal research, and a robust, current set of references.