Background/Context: Arizona's most recent English Language Learner (ELL) legislation, starting in the school year 2008-2009, requires all such students be educated through a specific Structured English Immersion (SEI) model: the 4-hour English Language Development (ELD) block. The basic premise behind this particular model is that ELL students should be taught the English language quickly so they can then succeed academically. Purpose/Objective/Research Question/Focus of Study: This study is the first attempt to look at a random sample of school districts across the state of Arizona under the 4-hour ELD block policy. The goal of the study is to better understand what are the positive aspects and the major challenges of implementing the 4-hour ELD block in Arizona. In particular this study aims to answer the following research questions: (1) How is the 4-hour ELD block being implemented? (2) What are the perceived benefits of the 4-hour ELD block for students and for schools? and (3) What are the district leaders' concerns about implementing the 4-hour ELD block? Population/Participants/Subjects: Of the 65 school districts randomly selected as potential participants, 26 agreed to participate in this study. The district response rate of the study was 40%, and the informants were the English Language Coordinators (ELC), who are the individuals most knowledgeable about how the 4-hour ELD block is implemented in their district. The sample of school districts that participated in our study is representative of the state of Arizona in terms of enrollment patterns. Research Design: The researchers designed a phone survey for ELCs. Qualitative data analyses were used to examine the responses of the 26 ELCs. More specifically, a coding scheme was created to assist in the process of organizing and analyzing the data. Findings/Results: Analyses reveal that the vast majority of ELCs think that, as a result of the program, there is an increased focus on English Language Learner (ELL) students' English language development. Regarding the challenges of the program, ELCs think that the implementation of the 4-hour ELD block has: a) neglected core areas of academic content that are critical for ELL students' academic success, b) contributed to ELL students' isolation, c) limited ELL students opportunities for on-time high school graduation, and d) assumed that English language learning can be accomplished within an unrealistic timeframe and under a set of unrealistic conditions. Conclusions/Recommendations: Given the data collected, we recommend that school districts explore alternative models of ELD instruction. These alternative models of ELD instruction need to take into consideration the local context of school districts, their resources, and existing research. Furthermore, we recommend that ELL students are offered additional programs or types of support that can help them become English proficient, while acquiring the academic content needed for succeeding in school. It seems reasonable to state that a combination of programs and support can be more effective than one prescriptive instructional approach. Finally, we recommend that school districts monitor progress and effectiveness by looking at multiple indicators. In particular, we strongly suggest that school districts keep track of reclassification, re-entry, and opting-out rates.