Factors associated with an unusually high rate of failure on the July 1991 National Council Licensure Examination for Registered Nurses (NCLEX-RN) were analyzed for nursing students at Angelo State University in San Angelo (Texas). Of the 111 nursing degree recipients who took the examination for the first time in July 1991, 18 (16.2%) failed. These 18 candidates were compared with 18 who were randomly selected from among those who passed. The results show that those who performed above average in the biological sciences tended to pass the NCLEX-RN on their first attempt. In addition, performance on the Mosby Assess Test (MAT) (a NCLEX-RN practice examination) had a statistically significant direct effect on NCLEX-RN performance. Based on a prediction model, the MAT alone was able to classify students accurately as passing or failing the NCLEX-RN 83.3% of the time. Key background variables (i.e., race, age, American College Testing Program score, and admission status) were able to accurately predict success or failure on the NCLEX-RN 86.1% of the time. Predictive formulas are described and offered as ways to use the assessment findings from this report. Students who are better prepared academically on admission and who continue to perform above average tend to pass the NCLEX-RN whether or not they take the nursing review course, have different instructors or laboratory times, or are male or female. Implications for improvement of nursing education are discussed. Four tables and two figures present study data. (Author/SLD)