This study provides a comprehensive picture of age differences in self-esteem from age 9 to 90 years using cross-sectional data collected from 326,641 individuals over the Internet. Self-esteem levels were high in childhood, dropped during adolescence, rose gradually throughout adulthood, and declined sharply in old age. This trajectory generally held across gender, socioeconomic status, ethnicity, and nationality (U.S. citizens vs. non-U.S. citizens). Overall, these findings support previous research, help clarify inconsistencies in the literature, and document new trends that require further investigation.