The purpose of this study was to examine the relationship between the Measures of Academic Progress (MAP) reading Rasch unIT (RIT) score and State of Texas Assessment of Academic Readiness (STAAR) and Texas English Language Proficiency Assessment System (TELPAS) reading achievement among English learners in Grades 8 and 9. The study also investigated whether MAP assessment data can be utilized to anticipate future achievement on STAAR and TELPAS reading assessments for English learners in Grades 8 and 9. The data for this study were gathered from the archival records of a total of 1,642 students, including 987 eighth-grade English learners from eight different schools and 655 ninth-grade English learners from seven different schools. All schools were located within a single suburban school district in North Texas. The study utilized a quantitative design that included the collection of archival quantitative data consisting of student demographic information and numerical data in the form of assessment results. Data were analyzed using descriptive analysis, a Pearson product-moment correlation analysis, regression analysis, and ANOVA. A Pearson product-moment correlation analysis indicated MAP Growth Reading RIT scores had a strong correlation with both eighth- and ninth-grade STAAR and TELPAS reading scores. The results of regression analysis revealed MAP RIT scores were a significant predictor for STAAR and TELPAS exam results in scale score format and differed significantly across the levels of STAAR reading and TELPAS reading proficiency. Regression models were utilized to determine the MAP Growth Reading RIT cut scores that are most reliably associated with success at each STAAR reading and TELPAS reading proficiency level. These cut scores directly align with STAAR and TELPAS scale scores and can be utilized to make predictions about future English learners' reading achievement on STAAR and TELPAS reading assessments. The results of this study were all found to be statistically significant, confirming strong correlations between MAP Growth Reading RIT scores and STAAR and TELPAS reading scores. MAP RIT data was affirmed as a robust indicator for anticipating English learners' reading achievement on STAAR and TELPAS reading assessments. Results from this study should be utilized to encourage ongoing student identification for progress monitoring, goal setting, and targeted intervention. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]