This Stage I pilot study will employ a randomized, controlled, between groups design in which 70 opiate dependent patients seeking methadone detoxification will be randomized into one of two treatment conditions: ACT opiate detoxification therapy or Drug Counseling. Both therapies will be delivered in the context of a 5-month methadone dose reduction based on a linear dosing strategy. Efficacy variables will include: (1) abstinence rates during and 1-month after detoxification as assessed by regular urine screens; (2) retention of patients in treatment; and (3) patient satisfaction and treatment acceptability. Reduction in HIV/Hepatitis C risk behaviors and changes in psychosocial functioning (e.g., employment, family, legal) will also be explored, along with mediators/moderators of the therapy (i.e., experiential avoidance). Subjects will be recruited from Houston area methadone clinics and the general community via advertising and will receive methadone as part of this protocol. A 2-4 week stabilization period will precede the 5-month methadone dose reduction. During the dose reduction, participants will attend the clinic twice each week and will receive weekly therapy. Participants will be contacted for follow up assessments up to one month post treatment.