Editorial -- Part I: Best Practices and Studies -- Collaborative Information Seeking - From 'What?' and 'Why?' to 'How?' and 'So What?' -- Studying Collaborative Information Seeking: Experiences with Three Methods -- Situating CIS - The Importance of Context in Collaborative Information Seeking -- Procedures and Collaborative Information Seeking: A Study of Emergency Departments -- Collaborative Information Seeking in the Context of Leisure and Work Task Situations -- Part II: New Domains -- Learning through Collaborative Information Seeking -- A Proposed CIS Interface Based on the Analysis of Problem-Solving in Online Technical Support -- Collaborative Information Use with Technology -- Part III: New Thoughts -- A Probability Ranking Principle for Collaborative Search -- Affective Dimension in Collaborative Information Seeking -- Collaborative Information Seeking Around Big Data.