Chief Medical Officer and Group Vice President of Walgreens. Before joining Walgreens, Dr. Leider was Chief Medical Officer of Ameritox, and prior to that he was Chief Medical Officer of XLHealth. Leider also served as the Chief Medical Officer for HealthNet and was a physician executive at Harvard Pilgrim Health Plan. Dr. Leider is on the editorial boards of Physician Executive and the Journal of Population Health Management. He is also a founding board member of the Disease Management Association of America (DMAA) and served on the board of the Institute of Aging at the University of Pennsylvania. Dr. Lieder also served for six years as an attending physician at Brigham and Women's Hospital and faculty member at Harvard Medical School, and more recently as a faculty member at the Johns Hopkins Carey School of Business.