Individuals differ in their biological rhythms. Some persons are morning orientated, preferring morning hours for intellectual and physical activities, and others are evening orientated. Previous work on adults revealed correlations between this morningness-eveningness construct and different aspects of mental health and well-being; for example, depression and seasonal affective disorders were related to eveningness. We hypothesize that morningness-eveningness may be associated with behavioral variables as measured by Goodman’s Strength and Difficulties Questionnaire (SDQ). 150 girls and 150 boys form German secondary schools participated in this study. We used the Composite Scale of Morningness (CSM) to assess chronotype and the SDQ to assess behavioral difficulties. CSM scores correlated positively with pro-social behavior, and negatively with behavioral problems, hyperactivity, and the total problem score. These results suggest that adolescents with higher eveningness also have higher problems as measured by the SDQ.