This Phase II randomized controlled trial is testing the efficacy of a cell phone application called START for helping men who use stimulants like methamphetamine to get the most out of their HIV treatment.

1. Assigned male at birth;
2. Identifies as male;
3. Age 18 or older;
4. Reads and speaks English;
5. Continental US residency;
6. Reports ever having had anal sex with a man;
7. Self-reported HIV diagnosis for 3 or more months and currently taking anti-retroviral therapy (ART)
8. Reports a detectable viral load during past year OR no viral load test in the past 10+ months OR reports < 90% adherence to ART;
9. Screens positive for a moderate or severe stimulant use disorder in the past 3 months with an abbreviated version of the National Institute on Drug Abuse (NIDA)-modified Alcohol, Smoking and Substance. Involvement Screening Test (ASSIST);
10. Has an iPhone or Android smartphone;
11. Is willing to participate in an mHealth intervention

Exclusion Criteria:

1. HIV-negative or never tested for HIV;
2. HIV-positive men without a current ART prescription;
3. Does not return a viable DBS specimen at baseline for viral load testing
4. Not a sexual minority man

Identifies as male