This volume presents the proceedings of ECSCW 2011, the 12th European Conference on Computer Supported Cooperative Work. Each conference offers an occasion to critically review our research field, which has been multidisciplinary and committed to high scientific standards, both theoretical and methodological, from its beginning. The papers this year focus on work and the enterprise as well as on the challenges of involving citizens, patients, etc. into collaborative settings. The papers embrace new theories, and discuss known ones. They contribute to the discussions on the blurring boundaries between home and work and on the ways we think about and study work. They introduce recent and emergent technologies, and study known social and collaborative technologies, such as wikis and video messages. Classical settings in computer supported cooperative work, e.g. meetings and standardization are also looked upon anew. With contributions from all over the world,  the papers in interesting ways help focus on the European perspective in our community. The 22  papers selected for this conference deal with and reflect the lively debate currently ongoing in our field of research.

Dynamic Self-moderation in a Corporate Wiki to Improve Participation and Contribution Quality.-Digital Traces of Interest: Deriving Interest Relationships from Social Media Interactions.-Studying the Adoption of Mail2Tag: An Enterprise 2.0 Tool for Sharing.-Challenges and Opportunities for Collaborative Technologies for Home Care Work.-The Use of Narratives in Medical Work: A Field Study of Physician-Patient Consultations.-The Pendulum of Standardization.-MyReDiary: Co-Designing for Collaborative Articulation in Physical Rehabilitation.-Relation Work: Creating Socio-Technical Connections in Global Engineering.-Discriminating Divergent/Convergent Phases of Meeting Using Non-Verbal Speech Patterns.-"You Probably Shouldn't Give Them Too Much Information" - Supporting Citizen-Government Collaboration.-Theories of Cognition in CSCW.-Lest We Forget - The European Field Study Tradition and the Issues of Conditions of Work in CSCW Research.-Flypad: Designing Trajectories in a Large-Scale Permanent Augmented Reality Installation.-Characterizing Deixis over Surfaces to Improve Remote Embodiments.-VideoPal: Exploring Asynchronous Video-Messaging to Enable Cross-Cultural Friendships.-Mixed-Initiative Friend-List Creation.-What are you Working On? Status Message Q&A in an Enterprise SNS.-The Hugging Team: The Role of Technology by Visualizing Group Traces on the Web.-SCHO: An Ontology Based Model for Computing Divergence Awareness in Distributed Collaborative Systems.-Common Ground and Small Group Interaction in Large Virtual World Gatherings.-Collaboration in Augmented Reality.-How to Establish Coordination and Joint Attention?