DVAs offer drug-abusing offenders protected detention in a separate wing or group of cells. The target group consists of drug users who enter voluntarily. Admission criteria are an ability to speak Dutch, expressed motivation to stop taking drugs, and expressed willingness to participate in the therapeutic program. Program elements are individual and group counseling, support and information groups, and random urine testing twice weekly. Positive tests are punished by discharge from the program. The main program activities are sports and work. In support groups, the motivation for acceptance of aftercare is increased, and preparatory steps are taken. In 1994 there were 12 DVAs in the Netherlands, housing 314 detainees. In this evaluation, information was obtained from 86 male inmates who volunteered to enter the program at a Rotterdam jail; 42 inmates from other wings of the facility were also included as a control group. The evaluation found that after 1 year, the drug- free detention group more actively searched for and accepted treatment compared to the control group. No differences were found, however, between the groups in drug use; recidivism; or physical, social, and psychological problems. Possible reasons for the lack of significant behavioral change were the severe and multiple problems of the treatment group and the shortness of the average length of time in the program (mean stay of 3 months); 9- 12 months has been shown to be most effective. 5 tables and 38 references