Antifat stigma is pervasive, often incurring deleterious effects on well-being among fat women. Based on predictions from Social Identity Theory, we examined the relationship between fat group identification, individual and collective responses to stigma, body satisfaction and self-esteem among a community-based sample of fat women. Fat group identification was found to predict collective social change and body affirmation endorsement along with reduced support for individual change through weight loss. Fat identification also predicted a preference for affiliation with other fat people, stronger perceptions of size discrimination, and less antifat prejudice. Implications of creatively redefining fat to affirm self-worth are discussed.