Previous research on the structure of adolescent self-esteem has produced somewhat inconsistent findings. In the current project, we examined the factorial structure of self-esteem in 661 adolescents (Mage = 14.2, SDage = 0.6) who provided self-ratings on the Multidimensional Self-Esteem Scale. After additionally assessing self-esteem in 348 adults (Mage = 39.5, SDage = 12.8), we investigated whether the structure of self-esteem is invariant across age and gender. Results from confirmatory factor analyses revealed that self-esteem can be described as a multidimensional, hierarchical construct that is invariant across the two age groups and gender. Testing for latent mean differences between females and males revealed that female participants showed significantly lower self-esteem in the domains of social, academic, emotional, and body-related self-esteem as compared to male participants. Findings are discussed with respect to the structure and level of self-esteem as well as practical implications.