Two differential equations modeling the diffusion of use of cultural forms are developed as alternatives to an earlier model based on exponential epochs of diffusion. Both new models are similar in that they incorporate imitation and desertion effects, but differ in the manner in which these effects operate over the course of the diffusion of use. The model which has a Gompertz curve as its integrated form fits data from 17 instances of use diffusion better than the model which has a logistic curve as its integrated form and, in addition, is more parsimonious than the original exponential epoch model. The relationship between the observed values of the parameters representing imitation and desertion is discussed in the context of the process of use diffusion.