Introduction: In this report from the USIP PeaceTech Initiative, a team of scholars from George Washington University and American University analyze the role of social media in Syria's civil war. The report focuses primarily on group dynamics, activist organizations' use of online media, and the relationship between new and traditional media. It draws on a public conference held in Washington, D.C., in September 2012 with Syrian activists, Western journalists, and policy analysts, as well as on a private workshop held in April 2013 at Stanford University with academic researchers and leading research scientists from top technology firms. It presents novel empirical research on Twitter conversations about Syria that demonstrates important new findings about differences across Arabic and English users, and about the emergence of distinct, insular clusters of discourse. This report is part of the ongoing Blogs and Bullets project led by USIP's PeaceTech Initiative, in partnership with George Washington University's Institute for Public Diplomacy and Global Communication. It builds on two other reports, published in 2010 and 2012: "Blogs and Bullets: New Media in Contentious Politics" and "Blogs and Bullets II: New Media and Conflict After the Arab Spring."