Cleveland Metropolitan School District (CMSD) has witnessed an increase in the number of English learner students in grades K-12 over recent years, with students coming from more diverse backgrounds in race/ethnicity, countries of origin, and native language. This requires more support from the district to meet diverse needs in terms of languages, cultures, and educational supports. The Cleveland Partnership for English Learner Success--a partnership among CMSD's Multilingual Multicultural Education office, the research office and researchers from Regional Educational Laboratory Midwest--has prioritized identifying English learner student and school characteristics associated with student achievement and language proficiency. This will provide a step toward improving district and school supports for English learner students. Student and school data from 2011/12 through 2016/17 were obtained from the district administrative records. The study examined means and percentages of student and school characteristics and student achievement of English learner students in grades 3-8 from school years 2011/12 through 2016/17. The study team examined these characteristics for English learner students in grades 3-8 each year separately, enabling the team to identify stable patterns while helping to uncover changes over time. To explore associations with achievement, the study developed a series of regression models that correlated student and school characteristics with student performance on statewide assessments while controlling for other key characteristics. The study focused on the most recent year of English learner outcomes available--2016/17--to provide information that was most relevant to the current English learner student population and educational setting. Between 2011/12 and 2016/17, English learner students in the district increasingly spoke languages other than Spanish. The percentage of English learner students enrolled in the district newcomer academy increased, while the percentage of English learner students enrolled in bilingual schools decreased. The study also found that English learner students increasingly were enrolled in schools with school climate scores higher than the district average over the study period, and that the newcomer academy consistently had school climate scores more than a standard deviation above the district average. Student special education status and lower prior year assessment performance were consistently associated with lower current student performance. English learner students speaking Arabic tended to have lower levels of English language proficiency, while gifted and female students tended to have higher English language proficiency. Students had lower mathematics achievement when they attended a school with larger numbers of English learner students per bilingual paraprofessional, and lower speaking proficiency levels when attending schools with larger numbers of students per certified ESL teacher, but these school staffing characteristics were not clearly associated with the other student outcomes studied. School climate domains were positively associated with student speaking proficiency levels, but not with most other student outcomes. The study findings suggest further work to gain a deeper understanding of how school climate may support English learner student language proficiency and achievement; examining how specialized schools like the district's newcomer academy may support positive school climate; and considering the role of staff specialized to work with English learner students.