This study was prompted by the Arizona Department of Education's (ADE) interest in learning more about the progress of English learner students toward English proficiency in the early grades. The study examined, for the 2013/14 kindergarten cohort in Arizona, the English language proficiency of non-native English speaker students and their English language arts (ELA) proficiency (reading and writing at grade level) in kindergarten and by the end of grade 3. ADE wanted to inform its policy and practice to best identify and serve English learner students in the early grades. The study followed a statewide cohort of students from kindergarten entry in fall 2013 through grade 3 in spring 2017, drawing on ADE records on enrollment, assessment, and eligibility for English learner services. The study used descriptive statistics and multilevel modeling to analyze how students' English language proficiency level in kindergarten and selected student and school characteristics were associated with their English language and ELA outcomes in grade 3. [For the full report, see ED607060; for the appendixes, see ED607062.]