Collective threat is the fear that an in-group member's behavior might reinforce a negative stereotype of one's group. In a field study, self-reported collective threat was higher in stereotyped minorities than in Whites and was linked to lower self-esteem in both groups. In 3 experimental studies, a potentially poor performance by an in-group member on a stereotype-relevant task proved threatening, as evidenced by lower self-esteem among minority students in 2 experiments and women in a 3rd experiment. The latter study demonstrated the generality of collective threat. Collective threat also undermined academic performance and affected self-stereotyping, stereotype activation, and physical distancing from the in-group member. Results further suggest that group identification plays a role in whether people use an avoidance or challenge strategy in coping with collective threat. Implications for theories of social identity and stigmatization are discussed.