Empirical evidence and federal mandates support the notion that students with mental retardation (MR) should spend some or much of the school day in general education classrooms. This study investigated trends in state-level rates for placing students in different educational settings between 1989-90 and 1999-2000. The research utilized state-reported data published in the Annual Report to Congress on the Implementation of the Individuals with Disabilities Education Act. Results indicate that during the 1990s (a) identification rates remained stable, (b) the proportion of students labeled with MR placed in general education classrooms for some or much of the school day increased from 27.3% to 44.7%, (c) placement in separate settings decreased from 72.7% to 55.3%, and (d) the proportion of students with MR placed in separate facilities decreased by 46%. Evidence also suggests that the U.S. has reached a plateau in educating students with MR in general education classrooms. Implications and suggestions for future research are provided. (Contains 3 tables.)