Internet sites that support user-generated content, so-called Web 2.0, have become part of the fabric of everyday life in technologically advanced nations. User

A new, counterintuitive theory for how social networks influence the spread of behavior New social movements, technologies, and public-health initiatives often

A study of the phenomenon of emotion contagion, or the communication of mood to others.

This volume is directed toward researchers and health professionals with an interest in the interstices of social networks and health. It consists of original p