He studies how social networks influence, and are influenced by, problem behaviors like aggression, bullying, delinquency, substance abuse and dating violence. Current projects include a longitudinal study of the interplay of adolescent romantic relationships, friendships and aggression, a network analysis of cyberbullying, and a longitudinal study of 13 year olds and their use of social media, in partnership with CNN’s Anderson Cooper 360. He received his doctorate in 2007 at the University of North Carolina at Chapel Hill.