The purpose of this study was to investigate the impacts of English language learners (ELL) and socioeconomic status (SES) on Matthew effect or compensatory trajectory by analyzing students' English language arts (ELA) test scores. This study applied the concept of the Matthew effect or the compensatory trajectory in the ELA proficiency tests with the latent growth modeling (LGM) method in order to examine the existence of "the rich get richer, and the poor get poorer" phenomenon in the longitudinal data. This examination allowed researchers to analyze ELA scores' growth patterns from students with different ELL and SES status by discerning the relationship between the starting point (intercept) and rate of changes (slope). In this study, data were taken from three tests for 4th-grade and 8th-grade students in the 2014/2015 academic year. The test items were constructed based on Common Core State Standards (CCSS), which provided uniform guidelines for standardized multiple-choice items. The results showed that LGM provided an adequate model-data fit for ELA scores. The LGM analysis indicated that ELL and SES had different impacts on the Matthew effect or the compensatory trajectory for different grades. Implications for ELL teaching instructions and literacy assessment were discussed. [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/en-US/products/dissertations/individuals.shtml.]