This study was designed to explore sex, age, and personality differences in the way working people rated their own work competencies. A total of 723 working adults (mainly from Europe and the Middle East) completed a questionnaire which measured respondents self-assessed work competencies, self-rated intelligence, creativity, humor and ability to learn, core selfevaluations, and Big Five personality traits. Males rated themselves significantly higher than females on four competencies (Leading and Deciding; Analyzing and Interpreting, Creating and Conceptualizing; and Enterprising and Performing). Factor analysis revealed one overall factor. Regressing the total competency rating onto demography (age and sex), core selfevaluations, and the Big Five showed a clear interpretable pattern. Older, stable, open, conscientious, extraverts tended to rate themselves highest on overall competency. Extraverted males rated their creativity and sense of humor highest. Core self-evaluations added little incremental validity over the Big Five. Personal ratings of competence are a function of sex and personality which may systematically relate to actual competency behaviors.That is individual differences predict both self-ratings and actual behavior which are related. Using personal ratings of work behavior in appraisal procedures may be contaminated by humility and hubris effects associated with sex and personality. The first to explore self-ratings of the "Great Eight" competencies and to examine how individual differences influence selfperceptions of leadership competencies.