Duncan James Watts (born February 20, 1971) is a computational social scientist and a professor at the University of Pennsylvania.

Watts was past external faculty member of the Santa Fe Institute and a former professor of sociology at Columbia University, where he headed the Collective Dynamics Group.

He also presents some of his research from Yahoo and Microsoft, and comments on the work of some popular nonfiction writers like Malcolm Gladwell.

[20][21] 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.

"[22] 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.