This study examined the predictive validity of the 18 scales of the California Psychological Inventory (CPI) and of two scales of the Opinion Scale relative to success criteria in graduate school as measured by grades in individual courses, performance on the Master's Comprehensive Examinations (MCE), and graduate grade-point average (GGPA). Subjects were 107 graduate students in a master's degree program in Counselor Education. Scores on CPI scales of Self-acceptance, Responsibility, Tolerance, Achievement via Independence, and Intellectual Efficiency were correlated .18, .19, .20, .21, and .19 (all p < .05), respectively, with MCE performance. Scores on the CPI scales of Psychological-Mindedness and Flexibility were correlated .24 (p < .01) and .27 (p < .01), respectively, with MCE performance. Significant correlations of .22, .17, and .19, respectively, were also found between scores on each of the factors of Tolerance, Achievement via Independence, and Psychological-Mindedness and grades in Educational Foundations (FED) courses—all significant at the .05 level. Standing on Dogmatism was correlated inversely (-.33) with FED course grades and -.39 with MCE performance—both coefficients being significant at the .001 level. Finally, Externality scores were inversely correlated with MCE performance and GGPA with both coefficients being -.22 (p < .05). It was concluded that psychological measures representing personality characteristics afford only limited promise as predictors of success in graduate programs. It was recommended that further research be conducted concerning use of other personality instruments and college populations.