Vocational interests predict a variety of important outcomes and are among the most widely applied individual difference constructs in psychology and education. Despite over 90 years of research, little is known about the longitudinal development of interests. In this meta-analysis, the authors investigate normative changes in interests through adolescence and young adulthood. Effect sizes were aggregated from 49 longitudinal studies reporting mean-level changes in vocational interests, containing 98 total samples and 20,639 participants. Random effects meta-analytic regression models were used to assess age-related changes and gender differences across Holland’s (1959, 1997) RIASEC categories and composite dimensions (people, things, data, and ideas). Results showed that mean-level interest scores generally increase with age, but effect sizes varied across interest categories and developmental periods. Adolescence was defined by two broad patterns of change: interest scores generally decreased during early adolescence, but then increased during late adolescence. During young adulthood, the most striking changes were found across the people and things orientations. Interests involving people tended to increase (artistic, social, and enterprising), whereas interests involving things either decreased (conventional) or remained constant (realistic and investigative). Gender differences associated with occupational stereotypes reached a lifetime peak during early adolescence, then tended to decrease in all subsequent age periods. Overall findings suggest there are normative changes in vocational interests from adolescence to adulthood, with important implications for developmental theories and the applied use of interests.