PROJECT SUMMARY/ABSTRACT Twenty-five percent of children with HIV-infection have childhood wasting (low weight-for-height or low mid-upper arm circumference, and HIV-exposed uninfected (HEU) children are twice as likely to be underweight as comparable HIV-unexposed children. Wasting is known to promote morbidity, HIV-progression, and mortality among these children. Improving wasting prevention and treatment for children and in early infant diagnosis and HIV-care programs could not only improve the child health outcomes of these children, but also substantially lower the global burden of childhood wasting. This proposal will develop a novel two-way short message service (SMS) platform that targets key barriers to improving nutritional care for HEU and HIV-infected children. This intervention will combine a maternally administered malnutrition monitoring system (MAMMS) with infant and young child education (IYCF) delivered by SMS. After developing the intervention using participatory design methods, we will complete a proof-of- concept quasi-experimental trial of MAMMS-IYCF in the R21. If the R21 milestones are meet, we will use the R33 to conduct a randomized trial testing the effectiveness of MAMMS-IYCF at reduced the incidence wasting, and the duration of wasting treatment. During this trial we will also assess the cost and cost-effectiveness of MAMMS-IYCF, and to better understand which barriers are being successfully addressed by intervention we will measure its effect on key attitudinal and behavioral outcomes including trust in the healthcare system, intention to seek if a child becomes wasted, and IYCF knowledge. This trial will generate the evidence necessary to integrate MAMMS-IYCF interventions into existing HIV-mHealth programs across the globe, and improve the outcomes of children in early infant diagnosis and HIV-care services while also substantially lowering the global burden of childhood wasting.