In Spring 2006 California released its first ever school-level Academic Performance Index (API) scores for English Learners (ELs). These EL-API scores were based on California Standards Tests in English language arts and math taken in the spring of 2005. The new EL-API data make it clear that elementary schools vary widely in their ability to get their English learner students to meet the state's academic content standards in English language arts and mathematics. This is true even among schools that are relatively similar in terms of student ethnicity, parent education level, socio-economic level, and concentration of EL students. Why do these differences in achievement occur among California elementary schools serving similarly high proportions of low-income and EL students? Are the explanations similar or different from those found in a previous study? What, if any, specific instructional practices aimed at EL students might also be having an effect? This report summarizes what the authors found in response to these questions, and constitutes the first analysis of its kind of California elementary school practices and their relationship to the school's English Learner Academic Performance Index. (Contains 10 footnotes, 3 figures, and 1 table.)