This paper examines the international diffusion of HRM practices and aims at building a model of the role of expatriates in the international diffusion of HRM practices. We focus on expatriates who are in a position to transfer HRM practices, such as managers and HRM professionals. The dependent variable of this model is the diffusion of HRM practices, through both implementation and internalization. The purpose of this model is to describe this diffusion of HRM practices as the result of two distinct forces, one conveyed by parent company management, the other by the subsidiary's locals, revolving around expatriates.