This study utilized a mixed-methods approach to holistically examine single-sex and coeducational urban elementary mathematics classes through situated cognitive theory. Participants came from two urban low-income Midwestern elementary schools with a high representation of minority students (n = 77 sixth graders, n = 4 teachers, n = 2 principals). Findings demonstrate that African American girls made more math achievement gains in single-sex classrooms; single-sex classrooms might mitigate math academic stereotypes for students and teachers; and that important contextual factors play a role in these outcomes. Testing these factors is a step toward delineating a theory of change for single-sex education in urban public schools.