We present the first comprehensive model of effective (average) mobility and local-field mobility for holes in MOSFET inversion layers. The new semiempirical equation for effective mobility, coupled with the new local-field mobility model, permits accurate two-dimensional simulation of source-to-drain current in MOSFET's. The model accounts for the dependence of mobility on transverse and longitudinal electric fields, channel doping concentration, fixed interface charge density, and temperature. It accounts not only for the scattering by fixed interface charges, and bulk and surface acoustic phonons, but it also correctly describes screened Coulomb scattering at low effective transverse fields (near threshold) and surface roughness scattering at high effective transverse fields. The model is therefore applicable over a much wider range of conditions compared to earlier reported inversion layer hole mobility models while maintaining a physically based character.