This comprehensive handbook explores the many issues affecting children’s physical and mental health. Its coverage spans a broad range of topics, exploring the history and foundations of clinical child psychology as well as the discipline’s theories, research base, ethical and legal implications, and diagnostic systems, including the NIMH’s Research Domain Criteria (RDoC). The handbook examines family risk factors for children (e.g., parental stress, divorce, and depression) and provides leading-edge reviews of cognitive variables (e.g., theories of memory, executive function, theories of intelligence, theory of mind and cognitive tempo). In addition, it describes methods of assessment, including checklists, interviews, and methods of treatment (e.g., cognitive behavior therapy, mindfulness, and family therapy). Chapters focus on assessment of specific diagnostic categories, such as depression, anxiety, selective mutism, ADHD, and pediatric topics, including chronic pain, childhood cancer, childhood obesity, and toilet training. Finally, the book addresses such emerging issues as gender diversity, social justice, cyberbullying, internet gaming disorder and the impact of COVID-19.