The four-volume set LNCS 9296-9299 constitutes the refereed proceedings of the 15th IFIP TC13 International Conference on Human-Computer Interaction, INTERACT 2015, held in Bamberg, Germany, in September 2015. The 43 papers included in the third volume are organized in topical sections on HCI for global software development; HCI in healthcare; HCI studies; human-robot interaction; interactive tabletops; mobile and ubiquitous interaction; multi-screen visualization and large screens; participatory design; pointing and gesture interaction; and social interaction.