This book constitutes the thoroughly refereed joint post-proceedings of the Third International Workshop on Mining Ubiquitous and Social Environments, MUSE 2012, held in Bristol, UK, in September 2012, and the Third International Workshop on Modeling Social Media, MSM 2012, held in Milwaukee, WI, USA, in June 2012.

How to Carve up the World: Learning and Collaboration for Structure Recommendation.- A Topological Approach for Detecting Twitter Communities with Common Interests.- Using Geographic Cost Functions to Discover Vessel Itineraries from AIS Messages.- Social Media as a Source of Sensing to Study City Dynamics and Urban Social Behavior: Approaches, Models and Opportunities.- An Analysis of Interactions within and between Extreme Right Communities in Social Media.- Who will Interact with Whom? A Case-Study in Second Life Using Online Social Network and Location-Based Social Network Features to Predict Interactions between Users.- Identifying Influential Users by Their Postings in Social Networks.- Modeling a Web Forum Ecosystem into an Enriched Social Graph.

This book constitutes the thoroughly refereed joint post-proceedings of the Third International Workshop on Mining Ubiquitous and Social Environments, MUSE 2012, held in Bristol, UK, in September 2012, and the Third International Workshop on Modeling Social Media, MSM 2012, held in Milwaukee, WI, USA, in June 2012. The 8 full papers included in the book are revised and significantly extended versions of papers submitted to the workshops. They cover a wide range of topics organized in three main themes: communities and group structure in ubiquitous social media; ubiquitous modeling; and aspects of social interactions and influence.