Barbara Geller, MD, was born on April 21, 1939, and passed away on May 8, 2020, in St. Louis, Missouri at the age of 81 after a brief illness. She was widely known to members of the American Academy of Child and Adolescent Psychiatry and the broader field of child and adolescent psychiatry for her rigorous body of work on childhood mood disorders and more specifically for her pioneering work in the description and validation of prepubertal bipolar disorder. She was a prolific investigator, mentor, teacher, and clinician. When she chose to retire in 2009, she was at the height of her academic career.