Aggressive behavior is one of the most common reasons for referrals of youth to mental health treatment. While there are multiple publications describing different types of aggression in children, it remains challenging for clinicians to diagnose and treat aggressive youth, especially those with impulsively aggressive behaviors. The reason for this dilemma is that currently several psychiatric diagnoses include only some of the common symptoms of aggression in their criteria. However, no single diagnosis or diagnostic specifier adequately captures youth with impulsive aggression (IA). Here we review select current diagnostic categories, including behavior and mood disorders, and suggest that they do not provide an adequate description of youth with IA. We also specifically focus on the construct of IA as a distinct entity from other diagnoses and propose a set of initial, provisional diagnostic criteria based on the available evidence that describes youth with IA to use for future evaluation.