The goal of this clinical trial is to determine the effects of an app to reduce opioid and cocaine use when layered atop methadone treatment as usual among people using both opioids and cocaine. The main questions it aims to answer are:

• Do people who use the app remain in methadone treatment longer than people who receive only treatment as usual?
• Do people who use the app report using opioids and/or cocaine less often, and do they report better improvements in their quality of life, than people who receive only treatment as usual?
• Does using the app more lead to better methadone treatment outcomes among people using the app?

Participants in this study will be randomly assigned to receive either the app or methadone treatment as usual. Participants randomly assigned to the treatment as usual group will receive access to methadone services as normally provided, including scheduled access to medications, information about the consequences of opioid and other drug use, and any onsite services (including group based interventions and/or 12-step programs). Those randomized into the app-using group will receive all the same services as the treatment as usual group, but will also be given a phone with the app already installed, or will have the app installed on their existing phone if they already have one. At random times throughout the week, the app will ask participants to submit drug tests for opioids and cocaine, which participants will be able to do remotely without having to physically "go to" a testing site. For each test that demonstrates the participant hasn't used opioids or cocaine, the participant will be rewarded with money directly into a debit card. Participants will also be able to earn rewards for picking up treatment-related medications, attending onsite appointments, and other treatment-related activities.

This two-arm randomized trial will evaluate the impact of 48 weeks of the DynamiCare app-based CM (DCM) intervention on retention in methadone treatment and polysubstance use among 240 methadone maintenance (OTP) patients with comorbid opioid use disorder and cocaine use disorder. New enrollees in methadone maintenance at two community treatment programs will be randomly assigned to either methadone treatment-as-usual (TAU) at the OTP or methadone TAU paired with the DynamiCare Health app (TAU+DCM) including remote drug testing and monetary rewards for negative opioid and cocaine tests indicating abstinence. Data on methadone treatment retention will be obtained through OTP records, and follow-up assessments will be conducted at 3-, 6-, and 12-months post-enrollment.

The study will examine participant outcomes in the domains of three aims:

Aim 1: To determine the relative effectiveness of TAU+DCM compared to TAU alone in improving methadone treatment retention through 12-months post treatment entry.

Aim 2: To determine the relative effectiveness of TAU+DCM compared to TAU alone in terms of [AIM 2a] reducing opioid use and cocaine use; and [Aim 2b] improving other secondary outcomes including non-targeted substance use and quality of life through 12-months post treatment entry.

Aim 3: To explore app use patterns, acceptability, and perceived value of personalized content on opioid and polysubstance use through 12-months post treatment entry.

Inclusion Criteria:

1. Age 18 or older
2. Cocaine use (self-reported in the past 30 days)
3. Willing and able to provide informed consent

Exclusion Criteria:

1. Severe psychiatric disorders
2. On home detention
3. Visual impairment that would make the use of the phone app impractical
4. Living arrangement that currently restricts phone access