Clinical Research Directory

Inclusion Criteria: 1. Aged 18 years or older, 2. Reports intentional cocaine or methamphetamine use \>15 of past 30 days, 3. Urine positive for cocaine or methamphetamine and negative for opioids/fentanyl prior to enrollment 4. Be able to provide the names of at least 2 persons who can consistently locate their whereabouts. Exclusion Criteria: 1. Reports past 30-day intentional use of any opioid or ongoing use of an opioid antagonist (e.g., naltrexone) 2. Intends to leave area in coming year, 3. Unable to communicate in English or Spanish, 4. Any other condition that, in the PI's judgment, interferes with safe study participation or adherence to study procedures.