Collective angst reflects concern about the ingroup’s future vitality. In four studies, the authors examined the impact of ingroup extinction threat on the experience of collective angst. In Study 1, collective angst was elicited in response to a physical or symbolic ingroup extinction threat compared to a no-threat control group. In Study 2, the extent to which French Canadians expressed collective angst because of the perceived extinction threat posed by English Canada predicted desire to engage in ingroup strengthening behaviors. In Studies 3 and 4, the impact of a historical extinction threat was assessed. The extent to which Jewish people expressed thinking about (Study 3) or were reminded of the Holocaust (Study 4) resulted in an increased desire to engage in ingroup strengthening behaviors. Collective angst acted as a mediator of these effects. Implications of extinction threat for both intragroup and intergroup behavior are discussed.