Digital media is ubiquitous in most children's lives. 1 This fact compels us to determine how electronically mediated communications influence children at all ages and developmental stages. By understanding these effects, parents, teachers, clinicians, and policymakers can help fulfill their shared responsibility of improving the well-being of children. In response to this need, I established Children and Screens: The Institute of Digital Media and Child Development 4 years ago. Children and Screens promotes research on the effects of digital media on children, and supports the creation and use of objective, research-based guidelines and policies. This endeavor began with a series of one-on-one conversations with leaders in media effects research and related fields. These discussions informed Children and Screens' subsequent collaboration with the National Academy of Sciences, which culminated in the Arthur M. Sackler Colloquium "Digital Media and Developing Minds" held in October 2015, where nearly 200 of the world's leading media researchers in all disciplines gathered to share their knowledge. This supplement builds on what transpired at that event. It describes the current state of youth media effects research and points the way to the necessary next steps in this field. Children and Screens' President and Board of Advisors asked members to lead interdisciplinary Working Groups and co-author articles to address specific, predefined topics within 3 large domains. Topics were chosen on the basis of core areas of inquiry that have already or are currently in the process of framing the evolving field of children and media. The Working Groups consisted of 107 Children and Screens members and 33 additional experts from diverse disciplinary and institutional perspectives who were invited by Working Group leaders on the basis of their particular competencies, with recommendations from Children and Screens members who expressed interest in participating. Children and Screens communicated to all Working Group leaders its strong desire for objectivity, appropriate balance, and range of expertise. As a result, this supplement reflects contributions not only from pediatrics, but also from the fields of