This article is driven by two interrelated questions. First, is the Internet enabling organizational change among traditional interest groups and political parties, such that they are starting to resemble the looser network forms characteristic of social movements? Second, what role is the Internet playing in new, conceptually intriguing citizen organizations such as MoveOn, the U.S.-based but internationally oriented entity? I develop the concept of repertoires to argue that the Internet encourages “organizational hybridity.” This captures two trends. First, established interest groups and parties are experiencing processes of hybridization based on the selective transplantation and adaptation of digital network repertoires previously considered typical of social movements. Second, new organizational forms are emerging that exist only in hybrid form and that could not function in the ways that they do without the Internet and the complex spatial and temporal interactions it facilitates. These “hybrid mobilization movements” (including MoveOn, the example considered here) blend repertoires typically associated with all three organizational types—parties, interest groups, and social movements. Moreover, I suggest that fast “repertoire switches,” spatially—between online and offline realms, and temporally—within and between campaigns, are emerging characteristics of contemporary political mobilization.