In this Yearbook we have looked at issues and new phenomena commonly emerging in developed countries for children and adolescents. Although many of the chapters are from Hong Kong, Chinas most international city, with a focus on Chinese children and adolescents, key developmental issues are reviewed and new research agenda are discussed with implications for other cultures and cities. We hope this Yearbook will be of interest to researchers who want to develop a new framework for understanding some of the most intriguing developmental issues of todays youth. In the chapters, they may find new perspectives and precious hints for planning future research. The Yearbook may also interest teachers, psychologists, social workers, and mental health practitioners in general, as they need to design prevention or intervention programs to reduce the risk factors for adolescents.