["Sociological Forum, Volume 36, Issue 3, Page 649-667, September 2021. ", "\nWhy are some US colleges and universities home to secular student organizations whereas others are not? Recent literature suggests that threat can inspire mobilization when groups perceive challenges to their rights or their social standing. Developing the concept of religious threat, I consider whether Secular Student Alliances (the country's largest association of student groups comprised of atheists, agnostics, and other religious skeptics) tend to be located at schools where secular students feel threatened by evangelical Christians. Through a logistic regression analysis of Secular Student Alliance presence across the 1953 4‐year, not‐for‐profit US colleges and universities, I first show that colleges and universities located in states and counties with a high percentage of evangelical Christians, and colleges and universities where activist‐oriented evangelical Christian organizations are located, are more likely to be home to Secular Student Alliances. Through qualitative content analyses of 47 Secular Student Alliance newsletters from 2014‐2017, I then show that student leaders indeed frame their groups as a way to counter threats posed by evangelical Christians. The article contributes to social movement theory on the mobilizing effects of threat and represents the most comprehensive study to date of secular student mobilization.\n"]