Moral panics have regularly erupted in society, but they appear almost daily on social media. We propose that social media helps fuel moral panics by combining perceived societal threats with a powerful signal of social amplification-virality. Eight studies with multiple methods test a social amplification model of moral panics in which virality amplifies perceptions of threats posed by deviant behavior and ideas, prompting moral outrage expression. Three naturalistic studies of Twitter (N = 237,230) reveal that virality predicts moral outrage in response to tweets about controversial issues, even when controlling for specific tweet content. Five experiments (N = 1,499) reveal the causal impact of virality on outrage expression and suggest that feelings of danger mediate this effect. This work connects classic ideas about moral panics with ongoing research on social media and provides a perspective on the nature of moral outrage. (PsycInfo Database Record (c) 2024 APA, all rights reserved).