What the previous post is really saying is that our juvenile justice system should not be so much of a juvenile justice system but more of a social work organization. I tend to agree with that idea, but I do not think that it will be possible to do so because of the high cost of that approach and because it is difficult to essentially go in to the homes of people with delinquent kids and force them to change their ways.
I think that the greatest improvement we could make in the juvenile justice system is to use more intensive forms of rehabilitation earlier. For example, when a child has behavioral problems in school, rather than waiting for the child to do a criminal act, the child should be placed in smaller classes and given more personal counseling and social support services. Also, the home situation should be investigated to see if there are elements of neglect and abuse. Early intervention, including making sure single parents with low incomes have adequate medical and day care and other support services can prevent children from becoming criminals.