Determining the most effective means of assessing content mastery as well as preparedness for the National Council Licensure Examination for Registered Nurses (NCLEX-RN) is a task of all pre-licensure nursing faculty. The records of 331 diploma nursing students were reviewed for this retrospective, descriptive, correlational study that examines the proficiency levels of the maternal/newborn nursing content mastery examination from Assessment Technologies Institute (ATI) as predictors of final course scores and first time success on the NCLEX-RN. Using a significance level of alpha=0.05 and a confidence interval of 95%, findings indicated that those achieving a level 3 proficiency achieved higher course scores than those who scored a level 2 proficiency, with a small effect size. Logistic regression results indicated that the ATI Maternal-Newborn content-mastery exam proficiency levels can predict first time NCLEX-RN success, with a small to medium effect size. In conclusion, ATI proficiency levels are a predictor of both final course scores and NCLEX-RN first-time success. Implications for practice include the potential to incorporate the ATI content-mastery exams as the comprehensive final exam in nursing courses; thereby, alleviating the need for faculty-generated final exams. Additionally, schools of nursing should continue to identify variables that affect content mastery as well as first-time pass rates on the NCLEX-RN. [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.]