The Moos Community Oriented Program Environment Scale (COPES) was administered to 244 adolescent clients and 131 drug counselors in 30“drug-free”outpatient drug treatment programs. Four of the COPES factor scores were found to predict significantly to treatment outcome (as measured by reduction in drug use): client ratings of“Spontaneiety,”and staff ratings of“Personal Problem Orientation,”“Practical Problem Orientation,”and“Order and Organization.”The more positive the ratings of the program environments, the greater the reduction in client-reported drug use from admission to discharge. The“discrepancies”(differences) between staff and client perceptions of the programs on two of the COPES factors (“Autonomy”and“Staff Control”) were also found to predict significantly to treatment outcome (as measured by reduction in drug use). The greater the discrepancy, the less successful was the treatment outcome. In the programs in which the clients tended to perceive the staff as less encouraging of client autonomy and as exercising more control over the clients relative to the staffs perceptions of these relationships, the clients tended to have less successful treatment outcomes. One possible interpretation of this finding might be that in the programs which have client populations that are more poorly motivated and more resistant to treatment, the clients will not only tend to have poorer treatment outcomes but will also perceive the program environment more negatively and thus will tend to disagree more with the staff's perceptions of the program.