The Gulf of Mexico (GOM) continental shelf, extending approximately 1600 km from the Florida west coast to the U.S.–Mexico border, is a large sedimentary basin that has been the focus of much geologic study and surveys during the past 70 years, related mostly to oil and gas exploration. Relatively little attention has been focused on mapping and assessing offshore sediment character and resources, such as sand. It is increasingly recognized, however, that baseline scientific information on seafloor sediment character and composition is needed for managing and protecting natural resources and for providing information on sand availability and quality for potential use in a variety of coastal restoration and protection projects in all five of the states from Florida to Texas. The geomorphologic character and shallow sedimentary stratigraphy of the GOM shelf has been determined over geologic time by sediment inputs from rivers; sea-level fluctuations up to 120 m, resulting in transgressions and regressions of the shore; and frequent storms. These processes have resulted in deposition, reworking, and preservation of a variety of sand bodies, both on the seafloor and in buried, ancestral stream channels. Sand bodies of highly varying grain size, sorting, color, and composition are present throughout parts of the GOM inner shelf, varying greatly in size and number and often overlain or admixed with finer-grained, muddy sediment. The shelf sand bodies tend to be fine grained and are often mixed with muddy or organic detritus as well as carbonate shell material. The GOM shelf is mantled with sand mostly off the Florida shore, and sediments become progressively finer and muddier westward across the Alabama, Mississippi, Louisiana, and Texas shelf regions. The shelf off each state contains shoals that represent drowned paleoshoreline and buried, ancestral, stream-channel features that originated when sea level was lower than at present and the shore was farther seaward. These shoals offer the best promise as potential sand resources; however, further study is needed to refine these findings based on reconnaissance-scale work.