Four mixed layer (ML) models after Denman <1973> (KLD), Garwood <1977> (RWG), McCormick and Scavia <1981> (K), and Thompson <1976> (RT) were compared against an extensive water temperature data set collected in the central basin of Lake Erie during the summer of 1979. Results suggest that all four models are nearly equal in their ability to satisfactorily simulate surface water temperatures. However, if diurnal physical processes are of interest, then the model ability to simulate both the ML depth and the energy level associated with entrainment dh/dt becomes crucial. While three of the models, KLD, RT, and RWG, were satistactory in simulating the ML depth, only two of the models RT and RWG, were satisfactory in matching the energy levels seen in the entrainment spectra of dh/dt. This agreement suggests that the shear velocity ΔV entrainment scaling plays a critical role in the cycling of shallow depth mixed layers. ¿ American Geophysical Union 1988