The authors develop a theoretical framework of the fashion process and a mathematical model of that framework. Basic constructs related to an individual's motivations for adopting fashions are extracted from the fashion literature and related to the individual's fashion decision process. The individual-level model is then integrated into a societal-level framework that can be represented as a system of difference equations. The parameters of the system represent static interpersonal influence networks. The general solution for the system of difference equations is presented and the dynamic implications of several interpersonal influence patterns assumed in previous research are derived mathematically.