DATOS-A is a multisite prospective treatment outcome study that collected data from 3,382 adolescent clients admitted to drug treatment programs from 1993 to 1995. All treatment programs were designed to treat adolescents and included the following three treatment modalities: residential therapeutic community, short-term inpatient treatment, and outpatient drug-free treatment. Participants were interviewed at intake, during treatment, and after treatment. This report focuses on data collected at intake and at the 1-month in-treatment assessments. To assess treatment compliance the study focused on three DATOS-A items from the 1-month survey. They were how much the client agreed on drug treatment goals with the staff person he/she saw most regularly, the client's difficulty or ease in doing what the drug program staff expected of him/her, and how closely the client followed the instructions and suggestions of the treatment staff. In addition to measures of self-perceived compliance, an objective measure of compliance was treatment completion, i.e., client involvement in the program for the planned duration of treatment. Stepwise logistic regression showed that the client's desire for help was significantly related to a higher degree of compliance with program expectations. Compared with those in residential treatment, those in inpatient treatment were more likely to agree with treatment goals, to follow instructions, and to stay for the planned duration of treatment. Those in outpatient treatment were more likely to meet treatment expectations. Psychological maladjustment was related to less self-perceived compliance. The implications of these findings for treatment policies are discussed, along with study limitations. 5 tables and 24 references