In the United States, the number of English Language Learners (ELLs) has steadily grown over the past decades. In the State of Delaware, the growth has been exponential. ELLs' academic underachievement in reading and math has remained a challenge for K-12 educational institutions. It has continued to be necessary to research the causes and potential solutions for closing the achievement gap between ELLs and non-ELLs. The purpose of this study was to determine whether there was a relationship between the Delaware Comprehensive Assessment System (DCAS) reading and math scores and the Assessing Comprehension and Communication in English State-to-State for English Language Learners (ACCESS for ELLs) four language domains and overall scores. Some student individual differences were also investigated. The data used for this study were obtained ex post facto. The data were analyzed using the Pearson product-moment correlation for all the inquiries. The participants were n = 231 ELLs from a local school district in Delaware. The study results showed that all the correlations between the ACCESS for ELL's four language domains and overall score and the DCAS reading and math assessments' scores were positive and significant. The correlations varied when disaggregated by the students' differences. Further research implications 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.]