Long-term and successful treatment outcomes among key populations (KPs) and other people living with HIV (PLHIV) will depend on lifelong adherence to antiretroviral therapy (TAR) and sustained viral suppression. The key to achieving this goal is the provision of client-centered, differentiated services in which the health system and community-based organizations facilitate continuous, lifelong ART in a manner that is responsive to KP members’ changing circumstances. EpiC’s new guide fills a gap for guidance specific to KP programming for strengthening ART retention. It includes recommendations on the provision of services across the treatment cascade that can speed up links to treatment; enhance differentiated, peer- and community-driven service delivery in partnership with facilities; and improve monitoring, tracking, and reengagement of individuals lost to follow-up to achieve viral suppression.