Inclusion Criteria:  Assigned male at birth; Identifies as male; Age 18 or older; reads and speaks English; Continental US residency; Reports any anal sex with a man in the past year; Currently has an active Antiretroviral Therapy (ART) prescription and reports less than excellent ART adherence (past 30 days); Screens positive for a moderate or severe stimulant use disorder with an abbreviated version of the National Institute on Drug Abuse (NIDA)-modified Alcohol, Smoking and Substance. Involvement Screening Test (ASSIST); Has an iPhone or Android smartphone; Is willing to participate in an mHealth intervention; Is willing to provide a Dried Blood Spot (DBS) specimen for viral load testing  Exclusion Criteria:  HIV-negative or never tested for HIV; HIV-positive men without a current ART prescription; Does not return a viable DBS specimen at baseline for viral load testing Not a sexual minority man