This article analyzes three decades of educational reform strategies pertaining to ethnocultural diversity in the United States and Canada and how they affect the efforts of four secondary schools, two in each context, to respond to increasing student diversity. Data include 186 teacher interviews drawn from a large ethnographic study. The article describes the current effects of increasing standardization on racially diverse schools and concludes with recommendations for policy reform that embrace poststandardization. (Contains 2 tables and 57 notes.)