In the early 1990's, in a national study of 95 public and private juvenile facilities, 73 percent of children in these facilities reported mental health problems during screening and 57 percent reported previous treatment for mental health problems. In Maryland, structured diagnostic interviews with young people in the state's 15 juvenile facilities indicated that 57 percent had a history of mental illness and 53 percent had at least one current mental disorder diagnosis. In Virginia, a census of 17 secure juvenile detention homes revealed that 8 to 10 percent of young people needed immediate mental health treatment for depression, anxiety, or psychotic symptoms; 77 percent met diagnostic criteria for a mental disorder and 55 percent had previous treatment for mental health problems. In Georgia, similar research found that 61 percent of young people in regional detention centers had mental disorders, including substance abuse disorders. In South Carolina, 72 percent of young people in juvenile detention facilities met the full criteria for at least one mental disorder diagnosis. Studies in various states have also identified prevalence rates for specific mental disorders. Individual risk factors for mental disorders in children and adolescents are considered, including biological influences, psychosocial risk factors, and family and genetic risk factors. The quality of mental health and substance abuse services provided to young people involved in the juvenile justice system is discussed, with emphasis on the lack of good prevalence data, inadequate screening and assessment, fragmented service delivery, and poor communication and coordination across systems. Strategies to improve service delivery focus on standardized screening and assessment, continuity of care, and mental health oversight committees. 8 references