Since the publication of Nostra Aetate in 1965, Jews and Christians have engaged in dialogue more systematically and broadly than ever before. Drawing on Romans 11:29, Nostra Aetate affirmed the ongoing covenant status of the Jewish People and rejected supersessionism, the notion that the Church has replaced the Jewish People as Israel. However, Nostra Aetate did little to define the relationship of the Jewish People and the Christian Church, which emerged as a major scholarly task. Within scholarly discourse of recent decades, the precise identity of "Israel" remains unclear. The identity of Israel lies at the heart of the Jewish-Christian theological relationship; without further clarity, dialogue will continue to face obstacles on central matters of concern. To contribute to such clarity, this dissertation asks, "Who is Israel: the Jewish People or the Christian Church?" and proceeds on the basis of a four-fold typology of logically possible answers: (1) Neither is Israel; (2) the Church alone is Israel; (3) the Jewish People alone is Israel; (4) both together are Israel. Four consecutive chapters analyze the four types of answers by examining key representative scholars, identifying the theological components constituting each's answer. More significantly, the deeper presuppositions underlying these theological convictions are identified and described in their relationship to one another, exposing the core unifying commitments of each group. A final chapter compares the constellations of deep presuppositions, discerning what is distinctive for each type of answer, thereby opening new pathways toward dialogue and constructive Jewish and Christian theologies of mutuality. The thesis is threefold: first, that the typology regarding views of Israel's identity defined and applied herein is a useful tool for understanding contemporary views on the question; second, that there are identifiable presuppositions that inform the types and can be analyzed in terms of unifying constellations of deep presuppositions upon which each answer is built; and third, that these constellations can be compared in order to see what is shared across types, and what is the core, distinctive set of presuppositions for each type.