Background: With rapid population aging, policy makers and service providers are becoming increasingly aware of the importance of building and maintaining age-friendly communities. Clearly, “age-friendly” relates to the impact of context on people’s well-being. But how? What is an age-friendly community, and does that differ for native and immigrant older people? Up until now, how native and immigrant older people in the Netherlands perceive community age-friendliness, and whether and how age-friendly communities help them realize well-being, remains unknown which limits opportunities to develop appropriate interventions. This article presents a study protocol to identify, theoretically and empirically, how and under what conditions age-friendly communities help native and immigrant older people in the Netherlands realize well-being. We present a theory-guided approach to elucidate differences in neighborhood age-friendliness and requirements for age-friendly community development between native Dutch and immigrant older people. Good interventions are built on good theory. The proposed research will add to theory building by systematically examining what older people get from their neighborhoods and the conditions that influence well-being realization, including the role of individual and neighborhood resources. We posit that physical and social well-being realization will be enhanced in age-friendly communities that support realization of multiple well-being needs and development of solidarity within and between groups in the neighborhood via cross-cutting sharing arrangements. Methods: We present a mixed-methods design among native and immigrant older people (Turkish, Surinamese and Moroccan) consisting of: (i) Q-studies (combining in-depth interview-based and quantitative analyses); (ii) a pilot survey study; (iii) a main survey study in Rotterdam, the Hague, Utrecht, and Amsterdam; and (iv) focus groups. Discussion: By exploring truly new ground in the field of age-friendly communities, the results of the ...