On the political and policy front, interest has increased in making communities more “age-friendly”, an ongoing trend since the World Health Organization launched its global Age-Friendly Cities project. We conceptualize age-friendly communities by building on the WHO framework and applying an ecological perspective. We thereby aim to make explicit key assumptions of the interplay between the person and the environment to advance research or policy decisions in this area. Ecological premises (e.g., there must be a fit between the older adult and environmental conditions) suggest the need for a holistic and interdisciplinary research approach. Such an approach is needed because age-friendly domains (the physical environment, housing, the social environment, opportunities for participation, informal and formal community supports and health services, transportation, communication, and information) cannot be treated in isolation from intrapersonal factors, such as age, gender, income, and functional status, and other levels of influence, including the policy environment.