The seasonal and interannual variability in the temperature, salinity, and volume of Shelf Water (SHW) in the Middle Atlantic Bight (MAB) is described for the period 1977--1999. Large interannual variations in the volume, salinity, and, to a lesser extent, temperature of the SHW occurred that were coherent over multiple year time periods. The variations in volume and salinity originated through processes acting outside of the MAB and were advected into the region from the Gulf of Maine. On a decadal average the SHW observed in the 1990s was approximately 1¿C warmer, 0.25 PSU fresher, and 1000 km3 more abundant than during the 1977--1987 period. The warming during the 1990s was largest in the southern part of the bight during the winter, when the SHW was more than 2¿C warmer then during the earlier decade.