The purpose of this research is to present a new model for understanding ethnonationalism: the dynamic ethnonationalism model, which depicts ethnic nationalism as an entity comprised of inherited elements as well as selective and changing ones. According to this new concept, ethnic nationalism, which is usually thought of as a “closed” given kinship, also has a flexible and voluntary nature, similar yet not identical to civic nationalism. Ethnic nationalism is indeed based on inherited elements—innate religion, descent, language, territory, etc., that are not subject to individual choice. However, each ethnic and sub-ethnic group re-interpret and re-implement these elements differently according to changing circumstances, perceptions and competing interests. This theory is examined through changes in immigration and naturalization policies which occurred in various ethnic states. The de- and re-ethnicization processes, the inclusion and exclusion trends engendered by changing boundaries of the ethnic collective, analyzed in this research, serve to illustrate the dynamic construction of ethnonationalism, managed by its multiple interest groups and policy makers. Following a concise review of the connection between ethnonationalism and citizenship throughout the world, the research delves into the Israeli case. The evolving boundaries of the Jewish-Israeli collective and the dispute concerning its definitions (“Who is a Jew”) offer a detailed demonstration of the dynamic ethnonationalism model. The Jewish-Israeli case, which is usually viewed as the ultimate example of rigid ethnicity based on religious stringencies, exhibits how ethnicity contains competing subjective interpretations (“Sub-Jew-ctivity”) that are simultaneously exclusive and inclusive. Thus, the integration of contradictory ethnic definitions into Israel’s laws and policies exhibits a dynamic, hybrid and “soft” ethnic national identity.