The phenomenon of multiple scattering of surface waves by two-dimensional viscoelastic particles is investigated. A method to evaluate the scattering amplitude is proposed and a simple equation which describes a nonlinear dependency of the effective wave number of transverse surface waves on the concentration of a two-dimensional colloid system is obtained. These results are used thereupon to investigate the propagation of capillary waves in a liquid with a heterogeneous surface film. For equilibrium films, effects of multiple scattering due to fluctuations of the surface tension can be neglected. However, for nonequilibrium systems which contain a heterogeneous solidlike surface phase, the nonlinear dependency of the real part of the effective wave number on the concentration of scatterers can be observed. The inhomogeneity of the dynamic surface elasticity can significantly influence the characteristics of surface waves only for condensed films with two-dimensional “bubbles” of the gaseous phase.