Young men who have sex with men (YMSM; ages 15-29 years) have rising HIV incidence in the United States. Pre-exposure prophylaxis (PrEP) is a highly effective medication prevent HIV infection, both at the individual and population level. However, in several clinical trials and demonstration projects among YMSM, a majority of participants had adherence to PrEP sufficiently low to compromise efficacy throughout the study. Unfortunately, pill-counts and self-reported adherence have limitations in this population, and therapeutic drug monitoring using previously available methods requires expensive equipment and specialized staff, meaning it cannot be implemented at the point-of-care (POC). The investigators have developed a novel POC test to measure urine drug-levels to PrEP for the first time, providing the opportunity to target and enhance adherence counseling during a routine clinical visit. Substantial knowledge gaps on the correct counseling approach and framing of the drug-level feedback message must be addressed to use this strategy to improve adherence among YMSM. This study will use a mixed methods approach to test the central hypothesis that an intervention leveraging a POC urine bioassay to detect PrEP adherence can both target and enhance adherence counseling. Brief interventions are a motivational interviewing (MI) counseling approach with wide uptake by primary care providers for substance use prevention and medical therapy adherence. PrEP2-BAY proposes a brief intervention be used as the framework for POC drug-level feedback among YMSM using PrEP. This study will test the acceptability, feasibility, and preliminary impact on long-term adherence, measured through hair tenofovir levels, of the brief intervention in a pilot randomized controlled trial among YMSM. This proposed research plan has the goal of optimizing PrEP's impact through a novel adherence support intervention. The findings of this proposal will lead to a R01 application to test a POC bioassay-enhanced adherence brief intervention among YMSM in a multi-city trial, with the goal of reducing the burden of HIV among MSM.