Executive function (EF) is a term used to describe the processes responsible for purposeful, goal-directed behavior and has been described as the "air traffic controller" or "CEO" of the brain. EFs are an important factor in overall quality of life, including school and job success. EFs are measured predominately through two different methods, performance-based measures and rating scales. Both measurement types are used in both clinical and research applications; however, they correlate poorly with each other, indicating they are measuring different constructs or different aspects of the same construct. Given the importance of academic achievement in children's lives, the functional outcomes of academics provide a reasonable gauge of the impact EF. The purpose of this dissertation was to examine the assessment of two EF components (working memory and inhibition) in relationship to the academic achievement of elementary students in three subjects (reading, mathematics, and science). Both studies completed in this dissertation used the Early Childhood Longitudinal Study--Kindergarten Class of 2010-2011 (ECLS-K:2011) database, a nationally representative sample sponsored by the National Center for Education Statistics. The first study focused on working memory in third-grade students. Students were administered a performance-based measure of working memory (a numbers reversed task), as well as academic assessments. The students' parent and teacher completed a working memory rating. The second study focused on inhibition in fourth and fifth grade students. Students were administered a performance-based inhibition measure (a flanker task) and academic assessments. Teachers completed an inhibitory control rating and an attentional focus rating. Both studies examined the relationships between the relevant performance-based measure and the ratings, as well as their relationship to academic achievement. Minimal to strong correlations were found across the two studies. Working memory and inhibition were both found to be correlated with academic achievement; however, the strength of the correlation varied by academic subject and assessment method. The performance-based measure correlated more strongly with academics than did the ratings across both studies. Mathematics achievement had the strongest correlation with both the working memory and the inhibition performance-based measures as compared to reading and science achievement. Ability of the EF measures to predict academic achievement and strengths/limitations of all measures are 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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]