This dissertation is an ethnographic account of global summit hopping activity during the six-year period after the 1999 protests against the World Trade Organization in Seattle. Summit hopping became an important form of transnationally-coordinated resistance to neoliberal capitalism and the free trade agenda for millions of activists who were part of a growing global network of social movements, struggles and tendencies that came to be known collectively as the global justice movement. As the most public and visible form of global justice activism during this period, summit protests were spectacular and unpredictable events through which activists created global spaces again and again in local places around the world. In my discussion of these spaces, I trace both regularities--in protest infrastructure, in forms of engagement, in policing routines, and in popular imaginaries of protest--and singularities--the locally particular conditions of each summit setting that interrupted and redirected activists' and observers' expectations about what global justice activism was about. Edge effects in the context of summit protests were the unpredictable dynamics of encounter among distinct activist groups and between activists, on the one hand, and police, media workers, and residents of host cities, on the other. These dynamics of encounter included adaptations, knowledge production, and hybridizations/ reformulations of projects; however, edge effects also included the distortions, myths, misrepresentations and exaggerations generated in official, popular and activist discourse about protesters and protest events. The ethnographic material is organized around three foci: (1) the physical composition of summit protests, with specific attention to the significance of security fences as edge markers in the practical and social dynamics of global justice activism; (2) summit protests as actualizations of global imaginaries in local places, with specific attention to the interactive encounters in the edges created between visiting protesters and local residents; (3) edge projects that emerged from global protest contexts but took on lives of their own, with specific attention to the Really Really Free Market project. In the events and relations described in this ethnographic material, edge effects are highlighted as a significant and productive dynamic of protests not often addressed in social movement scholarship.