A model of social identities constructed in terms of group membership is used to explore the incidence of cigarette smoking among adolescent girls. A sharp increase in girls' smoking at about 14 years of age related both to age and to puberty is demonstrated in a discriminant function analysis. The model is successful in identifying membership in never smoked and regular smoker groups but does not identify occasional smokers. Girls' ratings of 13 identity descriptors are summarised in similar, three scale nonsmoker and smokers identities. The nonsmoker identity is rated higher on the "mature" and "sensible" scales while the smoker identity is rated higher on the "fun-loving" scale and a fourteenth descriptor, breaks rules. The descriptors loading on the "mature" scale are contested suggesting that members of both smoking and nonsmoking groups value cool, popular, grown-up and makes up own mind. Material from focus group discussions demonstrates that the particular meanings of some descriptors may vary with group membership and values. Both the prevalence analysis and the focus group material support the hypothesis that interventions are best targeted at specific groups and that the occasional smoker identity needs to be targeted specifically in interventions designed to reduce smoking among adolescent girls.