A daily pill, PrEP, has changed HIV prevention and could help end the HIV epidemic in the U.S. Thus far, use of PrEP has not been evenly or effectively distributed. Much of the focus to date on PrEP delivery has been on linkage and initiation of PrEP. We know that effectiveness of PrEP depends not only on initiation, but also on adherence, which typically requires retention in care for ongoing monitoring and prescriptions per the CDC guidelines; i.e., persistence on PrEP. While the annual number of PrEP users has been increasing, improvement in retention and adherence has lagged, with many individuals who initiate PrEP no longer adherent or retained at 6 months, despite the likelihood that risk of exposure to HIV continues. Furthermore, some of the most vulnerable populations such as young Black MSM are more likely to fall out of PrEP care than their non-Black peers. Yet, measuring persistence has been challenging, particularly in a way that is standardized and can be used across patient populations and PrEP programs. Dr. Moira McNulty, from the University of Chicago, and Dr. Maria Pyra, from Northwestern University, will present their work on PrEP metrics, particularly around persistence, and how these metrics can improve equitable implementation of PrEP.