The four-volume set LNCS 8117-8120 constitutes the refereed proceedings of the 14th IFIP TC13 International Conference on Human-Computer Interaction, INTERACT 2013, held in Cape Town, South Africa, in September 2013. The 53 papers included in the third volume are organized in topical sections on mobile usage and techniques, mobile UX and privacy concerns, model-based user interface design, multimodal user interface design, multimodality, cross-platform studies, narratives in design, navigation aids, novel user interfaces, passwords: e-authentication, physical ergonomics, road safety, seniors and usability, social behaviour, collaboration and presence, social collaborative interaction, social media, and software development.