Measurements made across the edge of the Chesapeake Bay outflow plume in September 1996 are examined for evidence of the frontal head structure expected for a buoyant gravity current. Shipboard acoustic Doppler current profiler and hydrographic data from two distinct, 2-hour-long sets of frontal transects are analyzed. One set of observations was acquired just south of the bay mouth (near Cape Henry, Virginia) during late flood tide in water depth of 8 m. These measurements show a nearly steady frontal structure and a frontal head that is approximately 5-m deep and 20-m wide. The second data set was acquired about 20-km southeast of the bay mouth, where the plume bulges horizontally outward over the continental shelf. These measurements show a 9-m-deep frontal head (in water depth of 18 m) that ultimately dissipates during early flood tide. In both sets of observations, relative inflow of plume water into the frontal head is confined to a shallow surface layer estimated to be no more than about 2-m deep. Referenced to this layer, frontal propagation is supercritical (Froude number greater than 1). Also measured was an expected sinking motion (of the order of 3 cm/s) along the front. Overall, the results are consistent with previous measurements made across smaller buoyant plumes and in the laboratory, and they are compatible with the use of fixed values of Froude number and entrainment parameter in two-layer plume models. Additional study of the plume front during ebb tide is recommended.