George Frederic Still studied pediatrics and childhood conditions in England during the early twentieth century. In Still’s time, pediatrics, or the branch of medicine that focuses on treating and caring for children, remained largely unexplored according to biographer Joseph deBettencourt. Still helped advance pediatrics as a field by classifying and writing about diseases and conditions that arose in children. In 1897, he discovered a unique type of arthritis in children, now referred to as Still’s disease. Still also was one of the first to correctly describe what is now known as attention deficit hyperactivity disorder, or ADHD, a disorder that can cause children to act impulsively and have trouble focusing, among other behaviors. He shared his understanding of those conditions and pediatrics as a whole in a popular textbook called Common Disorders and Diseases of Childhood. Still’s work helped establish pediatrics as a separate field of medicine and provide a foundation for pediatricians throughout the twentieth century to understand and expand on a variety of conditions developing children can face.