Population health is a term encompassing "the health outcomes of a group of individuals, including the distribution of such outcomes within the group." Only recently have hospitals viewed themselves as focal points for promoting health in a community, involving themselves with population health. Hadassah Medical Organization (HMO), however, has been in the business of population health since its founding. Its early programs, promoting and delivering nutritional support, maternal-child health and other services to the Yishuv's inhabitants, showed that the HMO defined its community broadly. Hospital care came later. The HMO was established together with the Hebrew University Israel's first School of Public Health and Community Medicine in the 1960's, contributing >1200 Israeli alumni, and exposing thousands of medical students to population health. The School's founders developed Community-Oriented Primary Care, aimed at assessing and addressing health determinants and outcomes at the community level implemented in many centers worldwide. Reaching beyond Israel's borders, the School has trained a global public health workforce through its International Masters in Public Health with >820 graduates from 92 countries. HMO's researchers have made important contributions in the fields of epidemiology, health economics and policy and population health methodology as well as hospital and community quality of care. This article reviews HMO's contribution to population health at local, municipal, national and international levels. We will demonstrate the unique circumstances in Hadassah, Jerusalem and Israel which have enabled world-class research and training in population health, identifying important contributions to policy and service provision, as well as addressing future population health challenges.