Social Media -- Collaboration Using Social Media: The Case of Podio in a Voluntary Organization -- Keep Querying and Tag on: Collaborative Folksonomy Using Model-Based Recommendation -- Understanding Real-World Events via Multimedia Summaries Based on Social Indicators -- Social Networks -- How Do Researchers on Collaboration Technology Collaborate with Each Other? A Social Network Analysis -- Inferring Hidden Trust Relationships in Social Networks for Encouraging Collaboration and Cooperation among Individuals -- Providing Awareness, Understanding and Control of Personalized Stream Filtering in a P2P Social Network -- Crowdsourcing -- OurMap: Representing Crowdsourced Annotations on Geospatial Coordinates as Linked Open Data -- A Theoretical Model of User Engagement in Crowdsourcing -- Factors Influencing the Decision to Crowdsource -- Data Quality in an Output-Agreement Game: A Comparison between Game-Generated Tags and Professional Descriptors -- Learning -- Analyzing Two Participation Strategies in an Undergraduate Course Community -- Work and Learning across Boundaries: Artifacts, Discourses, and Processes in a University Course -- Redesigning Collaboration Tools to Enhance Social Presence in Online Learning Environments -- The Metafora Design Principles for a Collaborative, Interoperable Learning Framework -- Integrating Formal and Informal Learning through a FLOSS-Based Innovative Approach -- Using Geo-collaboration and Microblogging to Support Learning: Identifying Problems and Opportunities for Technological Business -- Collaboration Design -- Ontology-Based Resource Discovery in Pervasive Collaborative Environments -- Identifying the Awareness Mechanisms for Mobile Collaborative Applications -- In-Vivo Therapy Procedures: Design Process of a Geo-Referenced System -- Software Development -- Extending the Dependency Taxonomy of Agile Software Development -- Building a Domain Model for Mobile Collaborative Systems: Towards a Software Product Line -- Supporting Requirements Elicitation Practices.

This book constitutes the proceedings of the 19th Collaboration Researchers' International Working Group Conference on Collaboration and Technology, held in Wellington, New Zealand, in October/November 2013. The 18 revised papers presented together with 4 progress papers were carefully reviewed and selected from 34 submissions. They are organized into six thematic sessions as follows social media, social networks, crowdsourcing, learning, collaboration design and software development.