Background: The state of Arizona has recently mandated the Structured English Immersion Model (SEI) in the state's public schools, and as a result the local flexibility that existed regarding the choice of program models for ELLs has ended. In the school year 2008-09, these regulations were made even more restrictive after the implementation of what is now called the 4-hour ELD block model. Focus of Study: This report reviews achievement gaps in both reading and math between ELL and non-ELL students in Arizona over the period 2005-2009 and during the first year of implementation of the 4 hour ELD block, 2008-09. It also compares the progress of Arizona's ELL population towards academic proficiency relative to ELL students in two cities and states that do not place as restrictive legislation on ELL instruction: Utah and Washington, DC, two educational entities with vastly different spending policies. Research Design: Achievement was measured using the Reading and Math subtests of the Arizona Instrument to Measure Standards (AIMS), with data from the 2005-2009 administrations. To interpret gaps in performance, differences in AIMS mean scaled scores were analyzed. Two types of comparisons were made: 1) within-grade, across-year, and 2) across-grade, within-year. This allowed a more comprehensive understanding of trends in terms of achievement gaps. The comparison amongst different states was done separately. Data were collected from two sources: Applications for Race to the Top, and incentive program offered as part of the American Recovery and Reinvestment Act of 2009, were used for Utah and Washington, DC. Data from Arizona were gathered using publicly available state report cards released annually by the Arizona Department of Education. Findings: The study finds that Arizona has made little to no progress in closing the achievement gap between ELL and non-ELL students during this period. Here, the study argues that, notwithstanding changes in tests and proficiency thresholds in the states over this period of time, the relative position of Arizona vis-a-vis these comparison entities remains very similar, with Arizona continuing to lag behind both in percent of ELL students achieving proficiency in reading and math. Conclusion: The study presents recent evidence that suggests that Arizona is on the wrong path for closing achievement gaps for its ELL students and that this is due, at least in part, to its highly restrictive language instruction policies.