I am primarily interested in social networks and, particularly, how the flow of information influences, and is influenced by, network structure. How do groups reach consensus? Why do certain attitudes or behaviors become dominant in some groups but not others? Where do novel ideas come from? Along these lines I am concerned with the interconnection of selection- the tendency to become friends with those like ourselves- and harmonization- the tendency to become like those with whom we associate. While both processes doubtless play a role in generating homogeneity in a number of different settings, it is unclear how they interact. Indeed, their dynamic interaction may account for a great deal of the stability and change we observe in real social networks.