This study reports young people's assessment of own problems and strengths from a Norwegian survey (n=29,631, age range 10-19), based on the self-report version of the Strengths and Difficulties Questionnaire (response rate 84.3%). Differences according to the age and gender are illuminated. Girls reported most emotional problems and boys most conduct and peer problems. Compared to other countries, Norwegian adolescents reported more hyperactive behaviour. Total problem scores were highest in early-adolescence for boys (Mean=10.8, SD=6.1), and for girls it is in late adolescence (Mean 11.3, SD=5.2). One third of the subjects reported at least minor perceived difficulties. All symptom scales were strongly associated with perceived difficulties, impact and burden to others (P<0.001) with significant gender and age effects. Impact scores were included in the estimate of possible caseness. Combining symptom scores and impact scores, 3.7% of the sample was defined as a high risk group, while 8.8% needed special attention from mental health services. The results also suggested that SDQ could be a valuable screening instrument for older adolescents.