This survey of departments of corrections in the United States was undertaken to provide correctional staff with design, implementation, and management strategies to meet the needs of prisoners under the age of 18. The study examined what happens when individuals under age 18 are placed in adult correctional facilities, and explored the ways in which departments of corrections are attempting to deal with the growing population of youthful inmates. The following three objectives were the focus of this study: (1) to describe the number of incarcerated youths (at time of admission) being held in the nation's prison system, (2) to examine the different methods being used to house inmates under 18 years old, and (3) to explore different management approaches used with youthful inmates in terms of the size of the prison system and the area of the country in which they were located. For this study, respondents in 51 departments of corrections (50 states and the District of Columbia) were contacted by telephone regarding survey questions that were mailed prior to the phone interviews. The survey contained five questions concerning current practices for handling offenders under the age of 18 who had been placed in adult correctional institutions. Data were collected on the method used to house underaged inmates and the size of each system's population of inmates under 18 years old. Subsequently, the method and size data were combined to form categories describing four management approaches for dealing with offenders under the age of 18 in adult prisons: (1) separated/big, (2) separated/little, (3) integrated/big, and (4) integrated/little. Demographic variables include the population size and region (Northeast, South, Midwest, or West) of each jurisdiction, as well as the number and proportion of offenders under 18 years old within each state. Also present in the file is the location and name of the facility with the largest under-18 population in each jurisdiction.