'Adolescence, which has always been a period of increasing vulnerability to the onset of mental health problems, has recently also become the period of life when young people enter new digital realms. The impacts of digital media on healthy adolescent development is therefore an issue about which families, educators, policy-makers, legislators, and digital designers are all seeking answers. However, public discussion of this issue often produces more heat than light. This volume brings together an impressive list of experts to provide an up-to-date summary of the theoretical models and research findings that can guide a new evidence-based understanding of these issues.' Nicholas B. Allen, Ann Swindells Professor of Clinical Psychology, University of Oregon, USA