The authors found that four measures of legal pressure were either unrelated or negatively related to retention and outcome in five drug abuse treatment modalities. This suggests that nonvolunteer clients are likely to be insufficiently motivated to benefit fully from treatment and their presence may adversely affect staff morale and prognosis of volunteer clients. The authors recommend that legal pressure not be used as a basis for assigning applicants to treatment modalities and suggest that treatment outcome might be improved by procedures that 1) deal clinically with motivational differences between volunteers and nonvolunteers, 2) establish stricter motivational criteria for admitting nonvolunteers, or 3) encourage enforcement of existing sanctions against violations of stipulations to treatment.