This multi-site randomized controlled trial enrolling sexual minority men who use stimulants and are currently taking pre-exposure prophylaxis (PrEP). This randomized controlled trial will test the efficacy of a PrEP Affect Regulation Treatment Innovation (PARTI) condition comprised of a 5-session positive affect intervention delivered during smartphone-based Contingency Management (CM) for directly observed PrEP doses (PARTI+CM) compared to an attention-control condition delivered during CM. The primary outcome is HIV acquisition risk measured using a combination of tenofovir-diphosphate levels in dried blood spots that are indicative of sub-optimal adherence to PrEP and recent condomless anal sex.