 The last phase is a three arm, RCT that will test the efficacy of P3, a novel, theory-based mobile app that utilizes game mechanics and social networking features to improve PrEP adherence, retention in PrEP clinical care, and PrEP persistence among young men who have sex with men YMSM and young trans women YTW who have sex with men, ages 16-24. The investigators will test the efficacy of P3 and P3, which adds Next Step Counseling delivered by an adherence counselor through the app, against PrEP standard of care. Participants will be randomized to P3, P3, or standard of care. At intervention completion month 3, intervention arm participants who log in 2 times per week on average over the intervention period will be eligible for re-randomization to their initial intervention arm or escalation to LifeSteps for PrEP for Youth LSPY, a more intensive in-person adherence counseling approach in order to evaluate the combined approach. A cost comparison between P3 and P3 will be conducted. 