A punching shear strength mechanical model for RC slabs with and w/o punching reinforcement, based on a previous shear model developed by the authors, is presented. The identified differences between shear and punching resisting mechanisms have been incorporated into the governing equations and failure mode. The model provides consistent explanations to the experimentally observed behavior, such as the position of the critical perimeter, the influence of the moment transferred to the slab or the efficiency of the shear reinforcement. Good agreement has been obtained between the model results and those of an available large database of punching tests.