The article discusses the various roles of social workers in juvenile detention and adult criminal justice system in the U.S. According to the author, there are several opportunities and challenges for social workers in criminal justice despite of their absence in present years. It is stated that social workers played vital roles in the development of national policies to contract incarceration and poverty while increasing resources for education, employment and treatment in the community. Moreover, they play an important role in the development of treatment programs in prisons, jails and residential treatment centers.