A body of literature has increased our understanding of ethnic identity formation among ethnic minorities, but there remains a dearth of research focused on the ethnic identity formation of biethnic adolescents. Biethnic adolescents are likely to have unique experiences related to ethnicity that significantly alter the course of their ethnic identity formation. As such, a conceptual framework of biethnic identity is needed to guide future empirical work on biethnic identity and, ultimately, increase the field's understanding of this critical developmental process among biethnic adolescents. This article provides a review of theoretical and empirical work on ethnic identity among monoethnic adolescents, and, guided by the cultural ecological framework, an ecological framework of biethnic identity development is proposed. (Contains 1 figure and 1 note.)