The performance of the new UCD Advanced Canopy Atmosphere Surface model (ACAS) for use in mesoscale climate simulations is evaluated. Multilayer ACAS includes explicit calculations of kinematic and diabatic turbulent statistical moments to the third order within and above the canopy. ACAS also includes nonlinear methods for estimating surface energy balances. Comparisons of surface energy exchange and soil hydrology estimated by ACAS against observations at the Cabauw, Netherlands site for the year 1987 are analyzed and presented. ACAS performs comparably to the best performances of simpler surface exchange models tested against the Cabauw observations in the Project for Intercomparison of Land-Surface Parameterization Schemes (PILPS). On an annual basis, ACAS performs to within the errors of measurement for net radiative as well as sensible, latent, and soil heat flux densities with realistic representations of foliage density. Simulations of the diurnal evolution of surface energy flux densities yielded mid-day values within 15 Watts per square meter of observations without tuning. Sensitivity to uncertainties in vegetation density, significant in comparison to model performance, underscores the need for accurate vegetation specification. The simple canopy of the Cabauw site (8 cm cut grass) prevented a full test of the greater sophistication of ACAS, and further comparisons against observations in more complex vegetational regimes such as forests are forthcoming.