A mixed layer model is developed and applied based upon the model of Price, Weller, and Pinkel (Price et al., 1986). The new model includes diffusion, adds salinity to the calculation of density, and permits the assimilation of observed monthly mean salinity profiles. A simulation over a 2 year period on the inner part of the Newfoundland shelf shows that the new model performs well, much better than the previous model. The assimilation of salinity has relatively little effect, but the model results are sensitive to the parameterization of the vertical diffusivity. The best results are found for the case where the diffusivity is dependent upon N2; hence there is an indirect dependence on the salinity profile. The heat content of the model is simulated well except in late summer when there is too much heat in the model. ¿ American Geophysical Union 1995