There has been rapid growth in the study of diffusion across organizationsand social movements in recent years, fueled by interest in institutionalarguments and in network and dynamic analysis. This research develops asociologically grounded account of change emphasizing the channels along whichpractices flow. Our review focuses on characteristic lines of argument,emphasizing the structural and cultural logic of diffusion processes. We arguefor closer theoretical attention to why practices diffuse at different ratesand via different pathways in different settings. Three strategies for furtherdevelopment are proposed: broader comparative research designs, closerinspection of the content of social relations between collective actors, andmore attention to diffusion industries run by the media and communities ofexperts.