Research on vocational behavior has made progress in identifying broad personality traits associated with career indecision; however, important questions remain unanswered about the temporal stability of relationships between broad personality traits and Career Decidedness (CD), and about the role of narrow personality traits as predictors of CD, both of which were addressed in this longitudinal field study. A total of 2,046 undergraduate students completed an online personality inventory and CD questionnaire. A sub-group (N=267) responded to a follow-up questionnaire seven months later. Results indicated, as hypothesized, that CD correlated positively with the broad (Big Five) personality traits, openness, conscientiousness, and agreeableness. However, CD did not correlate as expected with the broad trait, extraversion, and correlated significantly and inversely with the broad trait, neuroticism, only for low-achievement students. Results showed that the narrow traits of optimism and work drive correlated significantly and positively with CD, and that these narrow traits accounted for more variance in CD (11.2%) than broad traits (.5%). CD correlated positively with chronological age, as predicted. However, Career Decidedness only increased through the first three of four years of college, and contrary to predictions, showed a non-significant decline in the senior year. In an unexpected finding based only on the sub-group who completed the second set of questionnaires, the relationship of personality and CD strengthened over the 7-month span of this study, yet instability within CD warrants caution. Results suggest questions for future research and implications for practice in vocational psychology.