A one-dimensional, two-layer, bulk-mixing model, driven by the climatic inputs of heat, fresh water, and wind, simulates the predominant evolving thermohaline characteristics of the shelf and slope waters in the Middle Atlantic Bight. The inclusion of sea surface temperature-dependent heating and implicit ''lateral fluxes'' has proven important to the model sensitivity and accuracy. The shape of the Margules frontal boundary separating shelf and slope waters depicts the transition from a monotonically sloping front of winter to the convoluted shape of summer, and suggests that the shelf-slope frontal shape is primarily density controlled. Cross-frontal diffusive fluxes of heat and salt are calculated, and their importance in relationship to features of the stratification such as the cold pool and the pycnocline salinity maximum intrusion is evaluated. The calculated cross-frontal salt fluxes are found to contribute a major part to the shelf water and cold pool salt budgets. Sensitivity studies establish that the model is most sensitive to parameters related to cross-pycnocline diffusion and that reasonable values of these parameters lead to simulations which agree with hydrographic observations. Further sensitivity studies show that, as expected, interannual variations in runoff should cause observable variations in shelf salinity, and that variations of wind speed should also cause significant hydrographic changes, but that the sea surface temperature is only moderately sensitive to air temperature variations.