No nationally available objective instrument is currently recognized as predictive of successful nursing program completion. Such a measure, available prior to program entry, might guide admissions procedures and be used to counsel applicants. This longitudinal descriptive-correlational study investigated the Watson-Glaser Critical Thinking Appraisal as a potential predictor of success as measured by a passing score on the NCLEX examination for nurse registration. From a southern Arizona population of 177 baccalaureate nursing students who graduated between December 1982 and May 1984, 145 graduates comprised the volunteer sample. These participants completed the Watson-Glaser Appraisal during their first week as upper-division nursing students, consented to participation in the study, and permitted reporting of NCLEX scores for use in statistical analyses. Fifty-three participants from this group repeated the Watson-Glaser Appraisal in the final month prior to graduation. Pearson Correlation for first semester total Watson-Glaser score and NCLEX score was .31 (p = .002). There was no significant change in total Watson-Glaser scores between first and last semesters as demonstrated by t-test. Multiple Regression analysis demonstrated that first semester Watson-Glaser scores and Entry GPAs together accounted for 15% of the variance in NCLEX scores (p = .001). Continuing data collection and analysis will expand the study population with 42 current graduates. Findings suggest that this instrument is not a valid measure of specific cognitive processes underlying the Nursing Process. Findings support the usefulness of the Watson-Glaser Critical Thinking Appraisal as a potential pre-admission predictor of nursing success.