This study investigated the stability and change of problems reported by adolescents during a 2-year period. An epidemiological sample of 580 adolescents aged 11-16 at the initial assessment completed the Youth Self-Report on two occasions. We found high stability in the level of Youth Self-Report total problem scores. The highest stability was found for aggressive behavior. Problem scores tended to increase across time. This increase was greater for girls than for boys, especially for the somatic complaints syndrome. Of the adolescents who could be regarded as deviant at the initial assessment, 42% could still be regarded as deviant 2 years later.