Food and nutrition insecurity (F&NI) are inextricably linked to the HIV epidemic, and their relationship is bidirectional. Although we have some understanding of the mechanisms by which HIV acquisition and disease progression lead to F&NI, the mechanisms by which F&NI increase the likelihood of HIV acquisition and disease progression have only recently begun to be investigated. Strikingly, the mechanisms by which F&NI affect the health of HIV+ pregnant women and their infants have not been investigated to date. However, preliminary data suggest that F&NI reduce antiretroviral adherence, gestational weight gain, and the duration of exclusive breastfeeding, all of which have consequences for the health of the mother and child, including vertical transmission. Therefore, the scientific objective of this K01 application is to elucidate the mechanisms by which F&NI have deleterious effects on the health of HIV+ mothers and their infants. My central hypothesis is that F&NI are detrimental to the health of HIV+ pregnant women and their infants via nutritional, disease, and psychosocial pathways. This hypothesis will be tested with 3 specific aims: (1) to describe and assess F&NI and associated modifiable determinants among HIV+ pregnant and lactating women in Kenya, (2) to characterize the magnitude and pathways by which F&NI impact maternal and infant health among a cohort of HIV+ pregnant women in Kenya, (3) develop a plan for a multi-level intervention to reduce F&NI to improve health of HIV+ mothers and their children. The qualitative research (for Aims 1 and 3) and cohort study (for Aim 2) will leverage resources at Family AIDS Care and Education Services, an HIV care and treatment program in Nyanza province, Kenya, the primary study site for several of my K01 mentors. My training in medical anthropology and international nutrition will serve me well, but I need additional mentorship and training in 1) assessment of F&NI among mothers and infants, 2) statistical analysis of complex longitudinal data sets 3) the management of HIV and HIV-associated diseases in low-resource settings, 4) assessment of psychosocial well-being and childhood development, and 5) the design, implementation, and evaluation of multi-level interventions. This training will further my long-term career goal of becoming an independent investigator with qualitative and quantitative expertise in the design and implementation of efficacious, culturally acceptable interventions that reduce morbidity and mortality of mothers and young children. The training and research are significant because F&NI is highly prevalent in sub-Saharan Africa, HIV+ pregnant women are disproportionately affected by it, and there are a number of potentially serious health consequences for women nd their infants. A better understanding of how F&NI is deleterious will provide knowledge to design more effective interventions to improve the health of HIV+ mothers and their HIV-exposed infants. This innovative research will generate novel data to test theoretically driven hypotheses about the pathways by which F&NI may impact the health of HIV-infected mothers and their infants.