This contribution is part of the Gulf Regional Sediment Management Master Plan and serves as a broad overview of the general setting, geologic history, coastal processes, hydrodynamics, and sediment sources for the Gulf of Mexico (GOM). The GOM is approximately 1,500,000 km². The five U.S. states bordering the Gulf comprise over 75,000 km of coastline. Gulf circulation is dominated by the Loop Current and gyres. The general trend of longshore sediment transport is in the westward direction west of the Mississippi River and in the eastward direction east of the Mississippi River, and is driven primarily by the wave and tidal energy. The GOM is a shallow basin and its climate is strongly dependent on precipitation and temperature averages. The general coastal climate is subtropical with warm to hot summers and cool winters with precipitation and high relative humidity throughout the year. The GOM coast is predominantly microtidal (<2-m range) with coastal processes and associated morphodynamics strongly influenced by storms. Tropical cyclones have affected every GOM coastal county or parish since 1900. Over 150 rivers flow into the Gulf; 85% of the fluvial water contribution is from U.S. rivers and of that, 64% is from the Mississippi River, which discharges approximately 2.4 billion kg of sediment annually. Humans are altering the natural coastal sediment budget through beach nourishment and dredging that affects the beach–dune sediment exchange. Six of the 10 most socioeconomically vulnerable coastal counties in the United States are in the Gulf region, which emphasizes the need for a sediment management master plan.