Four buried early Mesozoic rift basins on the Long Island platform region of the United States Atlantic continental margin were mapped, using seismic-reflection, magnetic, and gravity data. Low-angle normal border faults and high-angle cross faults control the structure of three of the basins, and some of these faults can be traced deep into the crust. Faulted basement blocks characterize the fourth basin. Adjacent basins form pairs in which the border faults dip toward each other and may have acted to localize crustal thinning. Two phases of rifting took place: an early stage characterized by widespread faulting leading to basin formation and a late stage characterized by uplift and erosion near the hinge zone and subsidence seaward of the hinge zone. The New York Bight basin, at the western end of the platform, may be an offshore extension of the Hartford basin. Paleozoic tectonic and structural trends are inferred to be the primary controls on the location of these basins, although our data are not specific enough to address local structural details.