The invetigators' objective is to implement Medication Assisted Treatment (MAT) and contingency management in patients affected by co-occurring opioid use disorder and stimulant use disorder. Participants will continue to receive standard of care for their opioid use disorder via MAT at our Outpatient Based Opioid Treatment (OBOT) Clinic. Participants' stimulant use disorder will be targeted through contingency management, with twice weekly urine drug screens and monetary prizes in exchange for negative urine drug screens. Through regular clinic visits and the use of incentives, the investigators hope to increase treatment adherence and increase the number of negative urine drug screens in subjects struggling with co-morbid opioid use disorder and stimulant use disorder. The investigators will determine whether or not this treatment is effective in this population, versus conventional treatment (baseline therapy patients were getting through OBOT). The investigators' primary outcome measure will be stimulant abstinence duration during the twelve week study.

Inclusion Criteria:

• Age 18 and older
• Patients treated for opioid use disorder in the Outpatient Based Opioid Treatment (OBOT) Clinic and who also struggle with stimulant use disorder but failed conventional treatment (positive urine drug screen for substances other than THC and buprenorphine)
• Ideal candidates will test positive for 3 out of 4 weeks or more prior to starting contingency management

Exclusion Criteria:

• Persons under the age of 18
• Persons not able to attend follow-up clinic visits
• Persons not able to consent