Background: Globally, undernutrition affects 372 million preschool children and 1.2 billion nonpregnant women of reproductive age (WRA). Challenges are particularly widespread in India, where 57% of WRA and 67% of 6–59-month-old children have anemia, and vitamin A deficiency is estimated to impact 19.1 million pregnant women and 190 million preschool children. This dissertation aimed to identify opportunities for nutritional assessment and intervention before and during the first 1000 days. Methods: Secondary analyses were conducted within three established research projects. Population samples included 6–24-month-old children and their lactating mothers and 15–40-year-old WRA in rural and urban Chittor District, Andhra Pradesh, and 12–18-month-old children living in slum areas in western Mumbai, Maharashtra. Results: The prevalence of anemia and vitamin A insufficiency (VAI) among WRA and young children was widespread. In Andhra Pradesh, anemia was present among a majority of 6–24-month-old children, and almost a third of their lactating nonpregnant mothers. In urban slum areas in Mumbai, a third of 12–18-month-old children had VAI. Prior to inflammation adjustments, more than half of women who were not pregnant or lactating had VAI, and different methods of inflammation adjustment produced contrasting retinol binding protein (RBP4) values. Anemia was significantly more likely among mothers who experienced adverse pregnancy outcomes and significantly less likely in women who had sufficient water in their homes. The odds of childhood anemia were significantly higher among children whose mothers were not paid for labor. In children, higher retinol was significantly associated with larger body composition characterized by mid-upper arm circumference. In WRA, RBP4 was significantly higher with greater age and body mass index and was significantly higher in urban areas compared to rural. Inflammation adjustment methods for RBP4 in WRA produced contrasting associations with vitamin A status. Conclusions: Undernutrition remains a widespread challenge in some of the most critical life stages. A standardized method for inflammation adjustment is still needed to assess vitamin A status in WRA. Increased biomarker surveillance, public health program evaluation and cross-cutting nutritional interventions are needed to identify optimal programmatic entry points to interrupt the cycle of malnutrition.