Background: Adolescent alcohol use continues to be a critical public health problem with both short- and long-term negative health consequences. Defining oneself in terms of alcohol, a drinking-related identity, has been shown to predict high levels of alcohol use. Because adolescence is the developmental period during which identity development is most salient, preventing the development of the drinker identity and early identification of youth who have a developing drinker identity may be important for prevention and early intervention. Methods: We review the theory- and evidence-based literature about identity development and the effects of a drinker identity on alcohol use behaviors in adolescents, discuss potential determinants of the drinker identity, and discuss future implications for practice and research. Results: There is some evidence that the drinker identity forms in early adolescence and becomes more well-developed during adolescence. The drinker identity predicts alcohol use behaviors both concurrently and over time in adolescence and young adulthood. There is also some evidence that early exposure to alcohol may contribute to formation of the drinker identity. Conclusions: Identity-based approaches may be promising strategies to identify adolescents who are at risk for alcohol use and to intervene with early prevention or treatment within the school setting.