Information technology can link geographically separated people and help them locate interesting or compatible resources. Although these attributes have the potential to bridge gaps and unite communities, they also have the potential to fragment interaction and divide groups by leading people to spend more time on special interests and by screening out less preferred contact. This paper introduces precise measures of “balkanization” then develops a model of individual knowledge profiles and community affiliation. These factors suggest conditions under which improved access, search, and screening might either balkanize or integrate interaction. As IT capabilities continue to improve, policy choices we make could put us on more or less attractive paths.