Used as a harm-reduction model and evidence based treatment for patients who already suffer from opioid use disorder. Goals include: 1. A decrease symptoms of opioid use disorder (such as illicit opioid use) 2. Decreased mortality 3. Reductions in criminal activity. MAT is offered in conjunction with psychosocial supports, which may include: 1. Alcohol and Other Drugs of Abuse counseling ; 2. Psychotherapy ; 3. Referral to social services such as employment and education assistance. The APDS Medication Assisted Treatment (MAT) curriculum is designed in four phases: • Phase One - Evaluation/Stabilization (Weekly: 3 days of IOP counseling, 1 individual session (non-group day), and medical visit to include UDS) • Phase Two – Education/Implementation (Weekly: 3 days of IOP counseling, 1 individual session (non-group day), and medical visit to include UDS) can change to 1 Individual every other week • Phase Three – Transition (Weekly: One (1) 90 minute IOP group counseling session, 1 individual session (non-group day), and medical visit to include UDS) • Phase Four - Maintenance (Bi-weekly: 1 individual session, required to meet Medical requirements while in maintenance phase, group attendance not required but may attend group for additional support when needed)