This document provides an introduction to a volume examining the influence of electronic media on children's well-being. It summarizes that children now have near-constant access to multiple media platforms, and spend more time using media than any other activity except sleeping. The volume contains articles reviewing research on how media exposure relates to children's school achievement, cognition, social behaviors, and health. While research is limited on newer technologies, key findings indicate content is important, and effects vary based on a child's age, gender, and background. The goal is to separate evidence from claims not supported by research.