The experimental intervention, which has been described in greater detail previously (32 (link)), was derived from Life-Steps (18 ,19 (link)), and consisted of four weekly sessions and two booster sessions, which occurred two and three months after PrEP initiation. The intervention component of each visit lasted approximately 50 minutes. The first session included education about PrEP, a discussion involving the psychosocial context in which PrEP use would occur, a brief motivational interviewing exercise, and exploring the establishment of a regular dosing schedule. Session two began with an adherence check-in, then focused on understanding the clients’ experiences taking PrEP, and engaging in problem solving to address any reported barriers to adherence. Session three also began with an adherence “check-in” and then introduced sexual risk behavior education, identifying high-risk activities, and factors that could increase and decrease personal risk for HIV as well as other sexually transmitted infections. The session also involved a discussion about biological factors associated with HIV transmission (e.g., partners’ level of infectiousness, measured by plasma HIV RNA), and discussed ways to reduce their risk in the context of taking PrEP. Overall, the core components of the intervention focused on medication adherence, sexual behavior, and problem solving barriers to adherence. Session content was designed to be flexible, allowing patients to identify their adherence support needs. Optional modules provided a framework to help interventionists work with participants who were experiencing substance abuse or mental health concerns that were adversely impacting PrEP adherence. In the final weekly session, the nurse-counselor discussed PrEP adherence goals and prior session content, and the patient’s plans for continued PrEP use upon intervention completion. Booster sessions at months two and three were designed to offer an opportunity for the trained study nurse to monitor PrEP adherence via electronic real-time adherence monitoring in the absence of weekly support. Study nurses used booster sessions to review PrEP adherence over a longer time-span and to address barriers to adherence using problem-solving skills learned during the earlier sessions. For participants who identified no challenges to adherence, the study nurse used the booster session to review and refine the existing adherence plan and help them identify potential future barriers to adherence.