This book presents the most comprehensive study to date of the major biological, psychological and environmental predictors of criminal behavior, particularly violence, through a detailed analysis of nearly 1000 low-income black youths from their birth to early adulthood. By examining over 150 variables spanning the lives of these youths, the study concludes that both biological and environmental factors produce strong, and independent, effects on delinquency and adult crime among males and females, who are distinguished from their controls. Powerful influences on violence include behavioral disorders during youth, low school achievement, parents with a low educational level, an absent father, hyperactivity, lead poisoning, left-handedness and mixed dominance, soft neurological signs, and neurological abnormalities. Case study comparisons between the most violent males and females and their controls show that criminals evidence a higher incidence of lead poisoning, disobedience, head injury, and a history of epileptic seizures among themselves or their immediate family members. Violent females are also more likely to have a family member who was incarcerated. The results do not confirm the findings of previous studies indicating direct relationships between violence and early intelligence, mental retardation, socioeconomic status, or early central nervous system dysfunction. The author concludes that both biological and environmental factors, in interaction, cause crime. For example, whereas some factors, such as hyperactivity, can be genetically transmitted across generations, causing a biological predisposition to criminal behavior, hyperactive people, as adults, can in turn, create instability in their families, making their children more prone to criminality, an environmental condition. The author concludes that most factors contributing to criminal and violent behavior can be prevented because they have environmental origins that can be eliminated.