This comprehensive two-volume set brings together important contributions providing fundamental economic analyses of social networks and the central roles they play in many facets of our lives. The first volume consists of classic articles that model network formation and games on networks, as well as those on the identification of peer effects from an econometric viewpoint. The second volume provides empirical analyses of network effects on labor, education, development, crime and industrial organization, as well as some laboratory and field experiments.This set of indispensable papers, with an original introduction by the editors, will prove an essential tool to researchers, scholars and practitioners involved in this field.