Saudi students are required to take the General Aptitude Test (GAT), achieving a certain competency, in order to gain acceptance in matriculation programs, or to study abroad. GAT is surrounded with a great deal of controversy regarding it as a reliable admission factor for measuring a student's aptitude for success in higher education. The present study explores the relationship among the GAT scores, English proficiency scores and the cumulative grade point average (GPA) of Saudi Arabian undergraduate students in American Universities, focusing on the academic years 2010 to 2015. It comprises a data sample of 362 Saudi students who were enrolled in universities during that time period and who graduated in 2015. This is a correlational study that adopts a descriptive methodology. A multiple regression analysis with standardized regression coefficients determined the relationship of each variable and graduation GPA of Saudi students from the included American institutions. Examining the relationship between the GAT and success is a key issue in helping to determine whether to continue applying this test, to consider revising it, or to discontinue its use. This research is further tasked with determining the more effective factor among these variables. The study findings discern that: a) There were no significant correlations between graduation GPA and GAT scores; b) The GPA at graduation and scores on the Test of English as a Foreign Language (TOEFL) are significantly related in a positive direction; c) The scores on the GAT and the International English Language Testing System (IELTS) are also significantly related positively. Thus, albeit a small correlation, the better students perform on the TOEFL, the higher GPA they obtained at graduation from college. Therefore, based on this study, the General Aptitude Test was not reliable as an academic factor in its relationship with the success of Saudi undergraduate students studying in American universities from 2010 to 2015. [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.]