The automated analysis of social interactions has attracted increasing interest from the computer vision community. A great deal of meaning in social interactions is subtly encoded in the posture, movement, expressions, tone of voice, etc. of the participants. Extraction of meaning from such subtle cues requires novel analysis methods that go beyond standard techniques for the classification of actions and activities. The goal of this workshop is to define and explore new challenges and approaches for decoding subtle human behavior in social interactions. Relevant topics for the workshop include but are by no means limited to: Fine-grained description of social interactions Understanding group behaviors Decoding social networks based on patterns of interaction Face analysis and gaze tracking for extracting social cues Human gesture and action recognition Multimodal human behavior analysis New sensors for understanding human behavior Datasets for social behaviors The workshop invites interested participants to submit research papers (8 pages) presenting original research. In addition to research papers, the committee will also accept extended abstracts of ongoing or published work (2 pages). Submitted papers should follow the ICCV 2013 paper format, used for the main conference. All submitted papers will receive double blind reviews. Authors may choose whether accepted papers appear in the proceedings. We expect accepted papers will be presented either orally or as a poster, depending as resources allow. Please follow the CMT system to submit your manuscript.