This paper reviews key findings on juvenile mental health problems in boys, psychopathy, and personality traits, obtained in the first 14 years of studies using data from the Pittsburgh Youth Study. This is a study of 3 samples, each of about 500 boys initially randomly drawn from boys in the 1st, 4th, and 7th grades of public schools in Pittsburgh. The boys have been followed regularly, initially each half year, and later at yearly intervals. Currently, the oldest boys are about 25 years old, whereas the youngest boys are about 19. Findings are presented on the prevalence and interrelation of disruptive behaviors, ADHD, and depressed mood. Results concerning risk factors for these outcomes are reviewed. Psychological factors such as psychopathy, impulsivity, and personality are described. The paper closes with findings on service delivery of boys with mental health problems.