The academic success and English proficiency of ELL students are receiving more attention as a result of the growing number of ELL students and the demand for accountability and assessment in education. It is widely accepted that ELL students struggle on state standardized tests because they lack the cognitive academic language abilities needed to succeed on extensive subject evaluations (Thakkar, 2013). According to Abedi and Dietel, ELLs' academic performance lags behind that of other segments of population, and the attainment gap reduces only slightly over time (2004). The NWEA archival data of 6th, 7th, and 8th grade students who attended a Midwest area middle school in 2018-2019 educational year was used to investigate the question of whether or not middle school ELL students' academic achievement improved in integrated science during one year of instruction while becoming more English language proficient, and improved in integrated science significantly more than the native speakers' achievement in science after both groups completed a year of science instruction. The data were used to analyze trends over time and variation in changes over time among groups of individuals in terms of English language and science achievements. Paired t-test and analysis of variances were used to determine if there was a relationship between science achievement and English language proficiency. The results indicated that there was a significant improvement in academic achievement of ELL students in science during one year of instruction while they were becoming more English language proficient, and ELL students' academic achievement in science did not improve significantly more than the native speakers' achievement after both groups completed a year of science instruction. Findings may be used to develop strategies to improve English language skills of ELL students of the targeted school settings. Improvement in English language skills may allow ELL students to succeed in all subject areas. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]