PROJECT SUMMARY/ABSTRACT Zambia has one of the highest incidences of HIV in the world. Adolescent girls and young women (AGYW) are a particularly affected group because of their social and economic vulnerability. There is growing recognition of the importance of including adolescent boys and young men (ABYM) in HIV prevention research. During adolescence and early adulthood, boys have significantly lower HIV prevalence than AGYW. However, adolescent boys experience large increases in HIV prevalence in the years that follow, which thereby indicates that adolescence may be a critical time when boys should be engaged in HIV prevention. With this administrative supplement, we propose to add a cohort of ABYM to explore the efficacy of tailored multilevel interventions on HIV outcomes. The overall goal of the supplement is to assess gender differences related to both efficacy and implementation outcomes of the multicomponent interventions. We will develop tailored education materials targeted at ABYM to complement the SHIELD (Support for HIV Integrated Education, Linkages to care, and Destigmatization) education modules developed for AGYW. We will conduct similar interventions for ABYM as planned for AGYW in the community setting and support linkages to the Integrated Wellness Care (IWC) clinics already established for the parent study. We will select 300 ABYM from the previously enrolled cohort for inclusion in the study. As stated in the parent grant, we will compare (1) the SHIELD community intervention only, (2) SHIELD and clinic-based interventions, and (3) the standard of care. We will pursue the following specific aims in this administrative supplement: Aim 1 is to include ABYM in assessing efficacy at 6 and 12 months of the multilevel interventions at the individual (HIV knowledge, self-efficacy), interpersonal (social support, stigma reduction), and health system (clinic-based multiple services) levels on HIV testing, retention in care, and viral load suppression using a cluster randomized design and Aim 2 is to assess implementation outcomes and cost-effectiveness of the interventions targeted at ABYM to support scale-up and sustainability. Including a cohort of ABYM will enhance the study by supplementing the data gathered from the cohort of AGYW to understand the impact of gender equality and norms on outcomes along the HIV continuum of care. The findings from the supplement and parent grant will allow us to design a comprehensive program for adolescents that can be implemented in the community setting along with sustainable linkages to the existing health care delivery system.