Structures of Participation in Digital Culture, edited by SSRC Program Director Joe Karaganis, explores digital technologies that are engines of cultural innovation, from the virtualization of group networks and social identities to the digital convergence of textural and audio-visual media. User-centered content production, from Wikipedia to YouTube to Open Source, has become the emblem of this transformation, but the changes run deeper and wider than these novel organizational forms. Digital culture is also about the transformation of what it means to be a creator within a vast and growing reservoir of media, data, computational power, and communicative possibilities. We have few tools and models for understanding the power of databases, network representations, filtering techniques, digital rights management, and the other new architectures of agency and control. We have fewer accounts of how these new capacities transform our shared cultures, our understanding of them, and our capacities to act within them. Advancing that account is the goal of this volume.