Summary: The study focuses on the prevalence of emotional and behavioral problems in adolescents from a secondary educational level, and on the changes of such variables according to age and gender. The Youth Self Report (YSR) designed by Achenbach (1991) was administered to an urban sample of 1342 Catalan adolescents aged 11 to 16, recruited from 15 schools located throughout all of the municipal districts of Barcelona, Spain. The purpose of this study is to offer descriptive data for each YSR syndrome, and to analyze age and gender differences in behavioral and emotional clusters of problems as defined in the YSR. The results show that with age self-perceived maladjustment increases progressively in females from 11 to 16 years, and that the progression is only detected in boys between 11 to 14 years. The age differences on the behavioral and cognitive domain are similar for both genders, while age differences in emotional problems diverge.