The equation of radiative transfer is generalized to include a description of the state of polarization of the radiation and a description of the induced (stimulated) events simulaneously. It is found that the number of induced events can be simply expressed in terms of the Stokes parameters of the corresponding spontaneous radiation source and those of the radiation field. The Stokes parameters of the induced radiation source, however, involve time averages of the spontaneous source amplitudes and phases other than those involved in defining the spontaneous source Stokes parameters.