Watts is the author of the book "Six Degrees: The Science of a Connected Age" and "Everything is Obvious * Once You Know the Answer: How Common Sense Fails Us". Until April 2012, he was a principal research scientist at Yahoo! Research, where he directed the Human Social Dynamics group. Watts joined Microsoft Research in New York City by its opening on May 3, 2012. Watts describes his research as exploring the "role that network structure plays in determining or constraining system behavior, focusing on a few broad problem areas in social science such as information contagion, financial risk management, and organizational design." More recently he has attracted attention for his modern-day replication of Stanley Milgram's small world experiment using email messages and for his studies of popularity and fads in on-line and other communities.