A simple model is presented for studying the impact between a rigid sphere and a thin layer of relatively soft material supported on a rigid substrate. By assuming that the major loss of energy during impact is due to the plastic deformation of the layer, an approximate analysis is made for computing the energy loss for layer materials which obey an elastic, perfectly plastic stress-strain law. An analytical expression for the coefficient of restitution is derived, and a parameter which controls the rebound characteristics is identified. Experimental results show generally good agreement with the analysis.