Established in 1967 as the country's first multidisciplinary research center devoted to health economics, the Leonard Davis Institute of Health Economics (LDI) celebrates its 50th Anniversary in 2017. During the last half century, Colonial Penn Center -- LDI's headquarters building at the center of the University of Pennsylvania campus -- has been a national hub for collaborative research to improve the nation's health care system. It has also been a center for the education of tomorrow's health services researchers who will continue that mission. LDI's seminars and conferences on campus and in Washington, D.C. draw together leading experts from around the country to discuss the major issue of health services delivery and policy. The 50th Anniversary will be marked by a year-long series of special seminars, conferences and editorial features including profiles of LDI's past executive directors as well as some of its most accomplished alumni, the first two of which appear below.