The present study addresses the issue of age differences in 5 personality domains across the life span in a cross-sectional study. In contrast to most previous studies, the present study follows a methodologically more rigorous approach to warrant that age-related differences in personality structure and mean level can be meaningfully compared. It uses data on 50 items of the Five-Factor Personality Inventory (FFPI) available from a study in a large and representative Dutch sample (N = 2,494; age range: 16 to 91 years) conducted in 1996 for the purpose of establishing norms for the FFPI. After having established strict measurement invariance, tests were made for factor covariances to be equal across age groups, revealing structural continuity of personality. Additionally, factor variances were shown to be equal across age groups. A number of age differences in the mean level of the five personality domains emerged. Specifically, older adults were, on average, more agreeable and, especially, more conscientious than middle-aged and younger adults. Findings from our study suggest that both continuity and change may mark personality over the course of life. (Contains 4 tables, 1 figure, and 3 footnotes.)