The International Conference on the Theory of Information Retrieval (ICTIR) provides a forum for the presentation and discussion of research related to the foundational aspects of Information Retrieval (IR), including, for example, new or improved models of relevance, ranking, representation, information needs, and evaluation. The need for formal frameworks is universal across the many applications of information retrieval. In addition to the established approaches in IR, the conference encourages the submission of papers that are attempting to define new tasks, develop new search paradigms, or apply methods from related disciplines, such as natural language processing, machine learning, statistics, or quantum mechanics. Large-scale experimental studies are not required for ICTIR papers, although solid evidence (theoretical or empirical) in support of new theories is expected. ICTIR grew from a series of SIGIR workshops on mathematical and formal methods for IR held during the years 2000 to 2005 and organized by Sandor Dominich, Keith van Rijsbergen, Mounia Lalmas, and Iadh Ounis. In 2007, ICTIR became a full conference founded by Keith and Sandor. Until 2013, ICTIR was held biennially: 2007 (Budapest, Hungary), 2009 (Cambridge, UK), 2011 (Bertinoro, Italy) and 2013 (Copenhagen, Denmark). ICTIR has been supported by the BCS-IRSG throughout these years.