The 2010 Census revealed the extent to which today's metropolitan areas are growing increasingly diverse. At the forefront of this change are schools. Yet, research on school context continues to rely upon a traditional, cross-sectional bifurcation that designates schools as either diverse or not. This classification may be especially inaccurate for some educational outcomes such as whether schools are cultivating effective citizenship for a diverse democracy. Because of changing demographics, this paper considers whether a new framework for conceptualizing school racial composition, including the number and identity of specific racial groups and the stability of those groups, can determine more precisely the ways in which school diversity impacts students' citizenship learning. (Contains 3 notes and 6 tables.)