The new act has replaced both borstal training and imprisonment for juveniles (male or female under age 21) with a new determinate sentence of youth custody training. The legislation clearly intends to keep male juveniles out of adult prisons. Girls under 17 years old serving youth custody sentences may be held in either a youth custody center or a remand center, but not in prison. Selected adult women offenders, however, may be housed in these centers as well. These are generally women who have not committed serious offenses. The rationale for mixing girls and women in these centers is that their interaction will exert a mutually rehabilitative influence. To test the validity of this rationale, this study interviewed 254 female inmates of all ages and 134 prison staff, accompanied by the researchers' observations in the centers and an analysis of institutional records. The study extended from October 1982 to October 1984. Findings did not support the rationale for mixing women and girl offenders, as a significant number of the girls learned criminal techniques from the women and were also influenced to abuse drugs. The existing policy has emerged from a complex political relationship between practical and historical experience and a popular concept of female crime. Developments have derived from a narrow debate which has not addressed fundamental issues about the purpose of imprisonment and the differential management of male and female inmates. 20 references.