Having enough allied health professionals to accommodate the needs of facilities that care for the growing aging population is a concern for allied health educators. To address the high workforce demands for health science careers, schools offering medical imaging programs seek competitive selection models that predict success. To improve the chances of students completing and succeeding in health science programs, health science education programs require a competitive selection process. This process seeks to identify students who possess the academic ability to succeed. Using the input-environment-output model, the purpose of this retrospective correlational study was to determine the predictive validity among selective math grade point average (GPA), science GPA, and standardized test scores from the Psychological Service Bureau (PSB) Health Occupations Aptitude Exam, Test of Essential Academic Skills (TEAS), and RADT 1085 Radiographic Equipment Final GPA and outcome of interest, passing the American Registry of Radiologic Technologist (ARRT) radiography credentialing exam. Using logistic regression, two independent variables--PSB-HOAE/TEAS Score and BIOL 2114L Anatomy and Physiology II Lab--were found to be significant predictors of passing the ARRT radiography credentialing exam on the first attempt. Proportions tests for the PSB-HOAE and TEAS found no significant difference between the proportion of students who passed on the first attempt. [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.]