The four-volume set LNCS 6946-6949 constitutes the refereed proceedings of the 13th IFIP TC13 International Conference on Human-Computer Interaction, INTERACT 2011, held in Lisbon, Portugal, in September 2011. ((Text folgt)) The 46 papers included in the third volume are organized in topical sections on novel user interfaces and interaction techniques, paper 2.0, recommender systems, social media and privacy, social networks, sound and smell, touch interfaces, tabletops, ubiquitous and context-aware computing, UI modeling, and usability.