Cross-sectional age differences in the Big Five personality traits were examined in a nationally representative sample of Australians (N = 12,618; age range = 15-84). Extraversion, Neuroticism, and Openness were negatively associated with age, whereas Agreeableness and Conscientiousness were positively associated with age. Effect sizes comparing the youngest and the oldest sample members were usually medium to large in size. Item-level analysis revealed that although most personality descriptors showed patterns similar to those exhibited by their respective global traits, this was not always the case. Thus, investigations of narrower aspects of personality may reveal more nuanced age differences and may begin to explain contradictory results from different studies. (Contains 3 tables and 5 figures.)