The purpose of this quantitative correlational study was to determine if and to what extent an ELL student's SBELP-RC could predict his or her ACPELA-RC, ACPELA-WP, and ACP-A1. Study participants were ELL students in Grades 9 to 12, attending a Northern Virginia high school. A further purpose of this study was to investigate if and to what extent an ELL student's SBELP-WP could predict his or her ACPELA-WP. Systemic Functional Linguistics (SFL) and the Catell-Horn-Carroll (CHC) theory of cognitive abilities were the theoretical foundations for this study. The research questions investigated the potential prediction between SBELP-RC and ACPELA-RC, ACPELA-WP, and ACP-A1, and the prediction between SBELP-WP and ACPELA-WP. The WIDA Reading and Writing assessments and the VASOL-RC, VASOL-WP, and VASOL-A1 assessments were the instruments. Simple linear regressions were performed, equations were determined from scatter plots, and descriptive and inferential statistics (p < 0.001 in all cases) were compiled. Findings revealed that a 43% variance of ACPELA-RC was, a 34% of variance of ACPELA-WP, and a 12% variance of ACP-A1 were predicted from SBELP-RC. A 17% variance of ACPELA-WP was predicted by SBELP-WP. The relationship between each pair of variables exhibited a linear and positive relationship. Thus, an increase in one variable was associated with an increase in the opposing variable. [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.]