Abstract
The Toronto Adolescent Longitudinal Study was undertaken to examine personality development in a non-clinical sample of children from ages 10 through 19. Fifty-nine boys and girls, selected to represent the full range of behavior presentation in regular classrooms, have participated throughout the complete study. Each year the students and at least one parent participated in a full day evaluation during which a comprehensive battery of measures was administered to assess their psychosocial characteristics. Some exemplary results are presented regarding the personality functioning and associated characteristics of the group at age 13. Our results lead us to conclude that adolescence should not be considered as a homogeneous developmental stage. Young adolescents can be differentiated along a dimension of competence in personality functioning which is associated with differences in their clinical presentation, self concept and behavior patterns.