Two studies examined the effects of self-categorization on people's orientation towards health. In Study 1, making salient a social identity which did not advocate a positive orientation towards health led group members to report weaker intentions to engage in health promotion behaviours in the future than did making salient a social identity which had a more positive health orientation. Study 2 showed that orientation towards health is influenced by the intergroup comparative context in which social identity is made salient. When social identity was made salient via an upward intergroup social comparison, participants' evaluation of the in-group's health was more negative, but their commitment to performing health promotion behaviours in the future was stronger, compared to when that same identity was made salient via a downward intergroup comparison. The findings are discussed in relation to the emerging debate concerning the impact of social group processes on health.