The construction of positive mathematical identities (MIs) is a complex and central issue in school mathematics, where girls are usually “counted out” of the field. This study explores positive MIs (high achiever and positive relationship with mathematics) of 3 girls. We employed a nested model of identity based on a case study approach (i.e., female mathematics students nested within a cluster of students nested within a mathematics classroom). The results highlight diversity in how these girls experienced mathematics: They valued different forms of doing mathematics (independent and collaborative; wider and complex; and straightforward, procedure-oriented mathematics), showed different forms of engagement (detachment, protagonist and challenging, and compliant and support-seeker), and narrated different MIs (efficient, different, and responsible). The study also explores and discusses the roles of mathematical practice and belonging to different peer clusters in these different forms of identification.