The scientific rationale for this supplement is to support the Adolescent Medicine Trials Network for HIV Interventions (ATN) mission and overall aims. These supplemental funds are needed to cover unanticipated costs that were not budgeted in either the original Scientific Leadership Center (SLC) application (RFA-HD-23- 020) or the Operations and Collaborations Center (OCC) application (RFA-HD-23-021) but are critical to the successful execution of the ATN goals. All funds requested support core needs and gaps identified through collaborative consultation with members of the SLC, OCC and NIH and are for activities that are within the scope of the originally reviewed and awarded application. Based on our detailed review of the parent RFAs, we anticipated that all of these activities would have been included in the application put forth by the OCC. However, now that the network has launched, we have found that these critical gaps exist and re-budgeting from the prime award to cover these costs is not an option because all the awarded funds are obligated. Specific Aim 1: Advance a rigorous and innovative research agenda to end the HIV epidemic among adolescents and young adults (ages 13-24) in the US by establishing a robust ATN infrastructure that prioritizes and implements high-impact research. The administrative supplement will support research gaps in current ATN agenda, specifically addressing HIV prevention and care needs among youth impacted by alcohol use and aligning one of the currently supported protocols with a collaborative protocol in the HIV Prevention Trials Network (HPTN). Further, the supplement supports important aspects of successful research implementation, including enrollment and retention of participants through social media and eConsent and critical aspects of monitoring participant safety and pharmacovigilance. Specific Aim 2: Facilitate internal communication and external collaborations and idea exchange to optimize alignment with NIH priorities, address emergent opportunities and maximize network productivity and resources. The administrative supplement will support successful implementation and dissemination of ATN protocols. While the OCC is developing the ATN website, they do not have the capacity or expertise to create any recruitment/dissemination materials to be displayed on the website nor have they planned for any dissemination activities at the site level. Specific Aim 3: Develop and nurture partnerships that will ensure community and youth input at all stages of conceptualization, design, implementation, and interpretation of the research. The administrative supplement will support adequate representation of youth within the ATN. The Subject Matter Research Consultants (SMRC) are a core facet of the ATN and are being deeply embedded into all aspects of the project including as members of protocol teams, scientific leadership groups, and Communication and Dissemination Hub where they will provide ongoing consulta...