Although research on the dark figure of delinquency has produced valuable quantitative estimates of its size, prior research is mechanistic and atheoretical about the conceptual underpinnings of the crimes that go undetected by the juvenile justice system. Drawing on data from 253 adjudicated youth in residential placements in the Midwestern United States, the current study found that youth self-reported over 25 delinquent offenses for every one police contact. The dark figure of delinquency has a wide distribution with some youth reporting upwards of 290 delinquent offenses per police contact or arrest. Youth who exhibited more psychopathic features, who displayed temperamental profiles characterized by low effortful control and high negative emotionality, males, and those who were older had larger dark figures of delinquency. Findings provide support for general criminological theories that invoke psychopathy or temperament as important individual-level drivers of delinquent conduct, much of which never results in juvenile justice system intervention and thus never achieves legal resolution.