Objective: We investigated the phenomenology of aggression in a group of Psychiatrically referred children and in a comparison group of children. Introduction: Children (N=275) were evaluated at a pediatric psychopharmacology clinic in an academic medical center and compared with 100 non-referred children from the community. To assess the influence of several predictors on the child's level of clinical impairment we conducted stepwise regression analyses.. Results: Aggression occurred across many different psychiatric diagnoses in psychiatrically referred children. Aggression in referred children was more frequent, physical, intense, lasted for a longer duration per episode, was more resistant to intervention, and occurred at an earlier age of onset in contrast with comparison children. Controlling for psychiatric diagnosis and demographic variables, family income and number of aggressive episodes in the last 6 months were the only significant predictors of child impairment. Discussion: Phenomenologically, aggression may be more maladaptive in children with a psychiatric disorder compared with non-referred youths. These phenomenological differences in characteristics of aggression support the concept of an aggressive syndrome in psychiatrically referred children. Conclusion: Results support the need for development of specific treatment interventions for excessive maladaptive aggression independent of psychiatric diagnosis in referred children and adolescents.