Book excerpt: In Challenging Codes Melucci brings an original perspective to research on collective action which both emphasizes the role of culture and makes telling connections with the experience of the individual in postmodern society. The focus is on the role of information in an age which knows both fragmentation and globalisation, building on the analysis of collective action familiar from the author's Nomads of the Present. Melucci addresses a wide range of contemporary issues, including political conflict and change, feminism, ecology, identity politics, power and inequality.