Introducing the Issue Jeanne Brooks-Gunn (bio) and Elisabeth Hirschhorn Donahue (bio) Media technology is an integral part of children's lives in the twenty-first century. The world of electronic media, however, is changing dramatically. Television, which dominated the media world through the mid-1990s, now competes in an arena crowded with cell phones, iPods, video games, instant messaging, interactive multiplayer video games, virtual reality sites, Web social networks, and email. American children are exposed to all these media and more. The vast majority of children have access to multiple media. Virtually all have television and radio in their homes, and half have a television in their bedrooms. Most have Internet and video game access, and a significant portion has a cell phone and an iPod. The numbers joining social networking websites like Facebook and MySpace grow daily. Technological convergence, a hallmark of media use today, enables youth to access the same source from different, often portable, media platforms. Thanks to convergence, a teen can watch a television show on a computer long after the show has aired on television and can use a cell phone to surf the Internet. Children, particularly adolescents, thus have almost constant access to media—often at times and in places where adult supervision is absent. As a result, America's young people spend more time using media than they do engaging in any single activity other than sleeping. What do researchers know about how children and youth use electronic media and about how that use influences their lives? Is media technology a boon, one that leaves American children today better educated, more socially connected, and better informed than any previous generation of the nation's children? Or is it, as many voices warn, a hazard for vulnerable children—an endless source of advertising, portrayals of violence, and opportunities for dangerous encounters with strangers and possible exposure to pornography? The quantity and quality of research on these questions are uneven. Researchers have amassed a vast amount of solid information on older technologies, such as television and movies. But investigations of newer technologies and of the novel uses of existing technologies are far fewer in number and more [End Page 3] speculative in their findings. The pervasiveness of electronic media in the lives of children makes it important for policymakers, educators, parents, and advocates to know what researchers have discovered, as well as what questions remain unanswered. This volume focuses on the most common forms of electronic media in use today and analyzes their influence on the well-being of children and adolescents. To address questions raised by the proliferation of new electronic media, we invited a panel of experts to review the best available evidence on whether and how exposure to different media forms is linked with such aspects of child well-being as school achievement, cognition, engagement in extracurricular activities, social interaction with peers and family, aggression, fear and anxiety, risky behaviors, and healthy lifestyle choices. Because how children fare in each of these areas is influenced by multiple forms of media and even by interactions between different media, we organized the volume by children's outcomes rather than by media platforms. We also asked the authors of the articles in the volume to consider evidence for children and adolescents separately and to examine whether media use differs for boys and girls and for more and less advantaged children. Finally, we asked the authors to pay special attention to the quality of the studies on which their conclusions are based. The studies range from state-of-the-art randomized design experiments, to carefully done observational studies, to suggestive but less conclusive associational studies. Our goal has been to separate the scientific evidence from unsubstantiated claims and rhetoric that the topic has often generated. What We Have Learned One of the central points of Marshall McLuhan's widely popular 1964 book, Understanding Media, was that the content of electronic media, its "message," is simply beside the point—that in electronic media, unlike print media, "the medium is the message." This volume comes to a rather different conclusion. Content, it turns out, is critical to how media influence children. Key findings from each of the...