This report summarizes a research analysis examining instructional practices for positive impact on achievement of low-income, English learner students as measured by the English Learner Academic Performance Index (EL-API) and other achievement tests. The report provides additional interpretive information. Based on research that surveyed teachers and principals in 237 California elementary schools, four broad, interrelated school practices proved significant: (1) Use of assessments and data to inform efforts to improve student achievement; (2) Sufficient resources, in particular adequate and appropriate textbooks for every student, well-maintained facilities, and individual principal perception that the given school's teaching staff has strong teaching skills, academic content knowledge, enthusiasm about teaching, and the ability to raise student achievement; (3) Coherent curriculum and instruction that is aligned with state standards; and (4) Prioritizing of student achievement by both principals and teachers. The study also analyzed a subset of questions about specific EL instructional practices and teacher qualifications. Although not a comprehensive look, the results raise questions about what matters most when it comes to improving the achievement of English learners. Some findings support frequently cited recommendations for EL instruction; others do not. Contains 4 figures.) [For associated Research Brief, see ED496642; for Report of Finding, see ED496646. For corresponding documents of previous version of this analysis: ED491868; ED491576 and ED491595.]