J.M. Berger is an expert on extremism, terrorism and how bad actors exploit technology, especially the Internet and social media. He writes for The Atlantic and is a frequent commentator on television and radio, including a recent appearance on Fresh Air.

Berger just published his first novel, Optimal. His most recent non-fiction book, Extremism (MIT Press, August 2018), was named an Outstanding Academic Title for 2019 by Choice Reviews, a publication of the Association of College and Research Libraries. The Washington Post called ISIS: The State of Terror (co-authored with Jessica Stern) "required reading for every politician and policymaker." His first book, Jihad Joe: Americans Who Go to War in the Name of Islam, is the definitive text on the history of American jihadism.  

Berger has also authored and co-authored several groundbreaking studies on social media analysis, including the development of metrics for measuring influence, community detection and detecting the use of manipulative tactics online. He is a member of the independent advisory board of the Global Internet Forum to Counter Terrorism and has previously researched extremist ideologies and extremist use of social media for Google and Facebook.  

Berger is currently a research fellow with VOX-Pol and a PhD candidate at Swansea University's School of Law, where he studies extremist ideologies.