The social identity/self-categorization model of stress suggests that social identity can play a role in protecting group members from adverse reactions to strain because it provides a basis for group members to receive and benefit from social support. To examine this model, two studies were conducted with groups exposed to extreme levels of strain: patients recovering from heart surgery (Study 1), bomb disposal officers and bar staff (Study 2). Consistent with predictions, in both studies there was a strong positive correlation between social identification and both social support and life/job satisfaction and a strong negative correlation between social identification and stress. In both studies path analysis also indicated that social support was a significant mediator of the relationship between (a) social identification and stress and (b) social identification and life/job satisfaction. In addition, Study 2 revealed that group membership plays a significant role in perceptions of how stressful different types of work are. Implications for the conceptualization of stress and social support are discussed.