Developmental trajectories of personal and collective self-concept were examined among American Indian adolescents. Personal self-concept (self-esteem) and collective self-concept (American Indian identity, Euro-American identity, community-mindedness) were assessed 6 times over 3 years in 4 cohorts of adolescents from 3 American Indian cultural groups (N=1,252). An accelerated longitudinal design was used to estimate developmental trajectories from 14 to 19 1/2 years; parallel-process and covariate models were used to examine variation in trajectories. Both personal and collective self-concepts were generally positive and showed small gains; they were moderately related to one another and differentially related to cultural group, gender, and perceived social support. The findings highlight the complexity of self-concept for American Indian youth and the significance of both personal and collective identity.