This open-access handbook synthesizes current research on the impacts of digital media on children's development, drawing from interdisciplinary expert reviews. It explores cognitive, physical, mental, and psychosocial effects on youth, as well as media’s influence on relationships, family, culture, and society. The book also examines specific digital domains like education technology, video gaming, and emerging technologies. With a structured approach, it provides research summaries, future directions, and recommendations for stakeholders. Covering topics such as brain development, mental health, internet use, race, gender, parenting, cyberbullying, and media policy, it aims to support evidence-based actions for positive youth development in the digital age.