PROJECT SUMMARY/ABSTRACT Availability of antiretroviral therapy (ART) coverage to pregnant women for life through Option B+ has been a major advance in sub-Saharan Africa for maternal health; however, postpartum mothers living with HIV are at risk for disengagement from HIV care and treatment non-adherence. Postpartum women are an important population for efforts to improve HIV treatment adherence and addressing the role of HIV stigma is imperative in the South African context. HIV stigma is also a key driver of weight and body size in this population. Larger bodies have generally been preferred among women living with HIV to combat the perception of rapid weight loss being an outward sign of rapidly declining health and AIDS-diagnosis. However, there are concerns about excessive weight gain and adverse outcomes related to obesity in HIV positive populations, given ART associated weight-gain concerns on top of population level increases in obesity. Excessive gestational weight gain and postpartum weight retention are associated with poor maternal health outcomes including pregnancy- related hypertensive disorders, large for gestational age babies, increased cesarean birth rates, childhood obesity as well as maternal type 2 diabetes and cardiovascular disease. HIV stigma and cultural preferences must be addressed in interventions designed to improve HIV treatment adherence and postpartum weight retention in this population, necessitating a contextually tailored intervention. This proposal will develop and refine a lay health worker delivered multicomponent behavioral intervention to address the behavioral determinants of both HIV viral suppression and postpartum weight retention. Aim 1 will refine the planned intervention through participatory qualitative data collection with the patient population and key stakeholders. Aim 2 will evaluate the feasibility and preliminary efficacy of the postpartum weight reduction and HIV viral suppression intervention for postpartum women living with HIV. Aim 3 will assess the acceptability and perceived usefulness of the intervention and identify potential mechanisms of change to be tested in a future large-scale RCT. The proposed study will make a significant contribution to our understanding of intervention techniques to address both HIV viral suppression and postpartum weight retention among mothers living with HIV, a critically important population for improved prevention and care. Findings from this work will be used to develop an R01 application to test the efficacy of our culturally and contextually appropriate HIV treatment and postpartum weight retention intervention in a large-scale RCT.