Dr. McMillan is Editor-in-Chief of the textbook Oskis Pediatrics: Principles and Practice, and for 17 years she was Editor-in-Chief of Contemporary Pediatrics. She served as medical editor of the Infectious Diseases Sub-Board Examination for the American Board of Pediatrics for 15 years and was a member of the American Academy of Pediatrics Committee on Infectious Diseases from 2001-2007. She has also been a member of the Pediatrics Review Committee for the Accreditation Council for Graduate Medical Education, serving as Vice Chair from 2011-2012. She was Director of the Harriet Lane Pediatric Residency Program.
Dr. McMillan has been Chair of the Board of Directors of the American Board of Pediatrics and on numerous committees of the Board. She is a member of the Infectious Disease Society of America, the Pediatric Infectious Disease Society, and the American Academy of Pediatrics.