Introduction: Social Movements, Contentious Actions, and Social Networks: ‘From Metaphor to Substance ’?

It is difficult to grasp the nature of social movements. 1 They cannot be reduced to specific insurrections or revolts, but rather resemble strings of more or less connected events, scattered across time and space; nor can they be identified with any specific organization, rather, they consist of groups and organizations, with various levels of formalization, linked in patterns of interaction which run from the fairly centralized to the totally decentralized, from the cooperative to the explicitly hostile; persons promoting and/or supporting their actions do so not as atomized individuals, possibly with similar values or social traits, but as actors linked to each other through complex webs of exchanges, either direct or mediated. Social movements are, in other words, complex and highly heterogeneous network structures. Since the 1970s, analysts of social movements and collective action have tried hard to make sense of these structures, and their dynamics. That collective action is significantly shaped by social ties between prospective participants is not a recent 2 discovery (e. view of social movements as networks linking a multiplicity of actors (e.g. Gerlach and Hine 1970; Curtis and Zurcher 1973). More recently, however, interest in the relationship between social movements and social networks has grown both in the range of the topics addressed, and the depth of the research results. Although not all