This dissertation investigates the construction and maintenance of ethnic boundaries in the face of contestation over core values. The dynamics of American Jewish communal structures and American Jews' relationships to the state of Israel offer a case study for exploring questions of boundary-maintenance, diasporic nationalism, and the social power of emotion. Specifically, this dissertation asks how, given disagreement and struggle over the ways in which Jewish Americans relate to the state of Israel, Jewish organizations strategize to develop and maintain Jewish community. It argues that dominant American Jewish organizations act like a social movement in mobilizing American Jews to identify with a particular version of the Jewish collective, which contributes to nationalist and political goals. Contestation over the state of Israel is central to the organized Jewish community's efforts to produce and regulate Jewish identity. Dominant American Jewish organizations seek to shape collective identity in the face of growing challenge by reasserting three key emotional frames through which they promote American Jewish connection to the state of Israel. These frames, which draw from existing cultural understandings, beliefs, and practices, are: a sense of interconnectedness, interdependence, and love, which resembles and reflects the claim that the Jewish nation is family; a sense of the state of Israel as the potential culmination of the most noble of Jewish and liberal values, such that the state represents a collective fantasy of aspirations realized; and the dual sense of both vulnerability and power, as an historically persecuted people with access to substantial political and financial resources. These three main threads - familial love, collective fantasy, and vulnerability and empowerment - form the basis of the emotional disposition the dominant Jewish organizations seek to inculcate. Using qualitative data gathered through ethnography and content analysis, this dissertation argues that the performance of the prescribed emotional disposition towards the state of Israel facilitates and expresses a sense of belonging to the American Jewish collective. These emotions also operate as a boundary marker, disciplining Jewish identity and variations of belonging to the collective. American Jews who breach the boundaries of the collective through critique of Israeli state policies toward Palestinians face potential marginalization or exclusion. Finally, in looking at the ways in which American Jewish organizations make meaning out of, and regulate relationships with, the state of Israel, this dissertation argues that the collective identity making processes of American Jews have tangible implications in the lives of Jews and Palestinians in Israel and the Occupied Palestinian Territories.