Jonathan D. Klein is the Marron and Mary Elizabeth Kendrick Professor of Pediatrics and Chief of the Division of Adolescent Medicine at Stanford University. He is an adolescent medicine specialist and a health services researcher known for his leadership and expertise in preventive services, youth development and tobacco control, and for the translation of research into clinical and public health practice and global child health policy. He serves as the President of the International Association for Adolescent Health and as Treasurer and a Member of the Executive Committee for the International Pediatric Association, and as a Member of the WHO Strategic and Technical Advisory Committee for Maternal, Newborn, Child and Adolescent Health and Nutrition (STAGE). Prior to joining the Stanford faculty, he was Associate Vice Chancellor for Research and Executive Vice Head of the Department of Pediatrics at the University of Illinois at Chicago (2017-23) and Associate Executive Director at the American Academy of Pediatrics (2009-17), where he designed and led the Academy’s research, newborn survival and global immunization programs, and the AAP Richmond Center’s evidence-based advocacy for the elimination of children's exposure to tobacco and secondhand smoke. Most recently, he led the partnership between IPA, UNICEF and WHO to translate emerging evidence on COVID-19 into actionable guidelines for national child and adolescent health leaders.