Previous research has shown that traits from the domain of conscientiousness tend to increase with age. However, previous research has not tested whether all aspects of conscientiousness change with age. The present research tests age differences in multiple facets of conscientiousness (industriousness, orderliness, impulse control, reliability, and conventionality) using multiple methods and multiple samples. In a community sample (N = 274) and a representative statewide sample (N = 613) of 18- to 94-year-olds, self-reported industriousness, impulse control, and reliability showed age differences from early adulthood to middle age, whereas orderliness did not. The transition into late adulthood was characterized by increases in impulse control, reliability, and conventionality. In contrast, age differences in observer-rated personality occurred mainly in older adulthood. Age differences held across both ethnicity and levels of socioeconomic status.