The Institute for Strategic Dialogue (ISD) is running an experimental action research pilot project, funded by Open Society Foundations (OSF), which seeks to understand the potential impact of social media on attitudes and intolerance in Europe. This literature review has been produced to summarise existing knowledge on the role of social media in influencing social attitudes, particularly in relation to inter-group dynamics. Published in April 2012, this review also includes a number of recent case studies from the social media and campaigning sector.