The present study examines specific relations between reactive/proactive aggression and social-emotional skills in self-assessments of 1468 children and adolescents (9-19 years). Self-assessments for two subtypes of reactive and proactive aggression measured by the Differential Aggression Questionnaire (DAF) as well as for social-emotional skills assessed by the Self-Report Checklist for Social and Learning Behavior (SSL) were collected. Correlation analyses indicated negative relations to self-perceived social-emotional skills in almost all subtypes of aggression. Multi-level regression analyses revealed that both types of aggression can be explained by low perceived skills (self-control, self-assertion). Reactive aggression was associated with a high perceived empathy. Furthermore, reactive aggression was related to a lower age and proactive aggression to a higher age. Implications for clinical practice are discussed.