Current research on ethnic-racial identity (ERI) development among Black youth derives primarily from studies that focus on the impact of parental racial socialization from a racial/monoidentity perspective without accounting for the roles of youth's other worlds (i.e.,schools, classrooms, and peers) and the intersection of their social identities in their identity development experiences. In using Phelan, Davidson, and Cao's Multiple Worlds model as a framework as well as Black girls' own words, we explore the beliefs and attitudes Black girls hold about race and their own racial categorization, as well as the processes that contribute to their learning about race (and racism) during early adolescence. We find that the Black girls in the present study are making meaning of their ERI, in part, in response to stereotypical and biased messages about their identities within their multiple worlds (i.e.,schools, classrooms, families, and peers). The findings support the need for an expanded view of the messages and experiences that influence the ERI development process by illustrating that schools, classrooms, peers, and families are important socializing environments that influence the ERI development process for Black girls. [This is the online version of an article published in "Journal of Adolescent Research."]