Report on the SIGIR 2015 Workshop on Social Personalization and Search.

The use of contexts --side information associated to information tasks-- has been one of the most important dimensions for the improvement of Information Retrieval tasks, helping to clarify the information needs of the users which usually start from a few keywords in a text box. Particularly, the social context has been leveraged in search and personalization since the inception of the Social Web, but even today we find new scenarios of information filtering, search, recommendation and personalization where the use of social signals can produce a steep improvement. In addition, the action of searching has become a social process on the Web, making traditional assumptions of relevance obsolete and requiring new paradigms for matching the most useful resources that solve information needs. This escenario has motivated us for organizing the Social Personalization and Search (SPS) workshop, a forum aimed at sharing and discussing research that leverage social data for improving classic personalization models for information access and to revisiting search from individual phenomena to a collaborative process.