The World Health Organization estimates that globally, over 1.6 billion people are anaemic, with the prevalence highest among preschool children. Almost one third of the 293 million anaemic preschool children worldwide live in India. Despite rapid economic growth and long-standing anaemia control policies, the burden of anaemia in Indian children remains undiminished. In rural India, 80.9% of children aged 6-35 months are anaemic. Iron deficiency is believed to be the most important cause of anaemia in this population. However, other conditions, including deficiencies of folate, vitamins B12 and A, malarial and hookworm infection, and haemoglobinopathies, may also cause anaemia. The relative contribution of nutritional, infectious and genetic conditions to the burden of anaemia among Indian children has not been determined. A comprehensive understanding of the determinants of anaemia, including an appreciation of the performance of anaemia control programmes, is needed to address anaemia among young children in rural India. This thesis comprises two studies that aim to ultimately inform policy by understanding the determinants of anaemia, evaluating implementation of anaemia control strategies in the field, and ascertaining the value of screening for anaemia. The first project comprises a cross-sectional study investigating the determinants of anaemia and micronutrient concentrations, and evaluating the performance of anaemia control strategies in children 12-23 months of age in rural Karnataka, India. Of 401 children sampled, 75.3% were anaemic. A multiple regression model identified independent, positive associations between children’s haemoglobin and their ferritin, folate, age, maternal haemoglobin, and either family wealth or food security status; and negative associations with presence of beta thalassaemia trait, C-Reactive Protein (CRP) and male sex. Children’s ferritin was positively associated with maternal haemoglobin, iron intake and CRP, and negatively with continued breastfeeding and child’s energy intake. Children continuing to receive breastmilk had lower ferritin, B12 and vitamin A concentrations than their fully weaned counterparts, received less nutrition from complementary feeds and belonged to poorer, more food insecure families. Only 41.5% of children had ever received iron supplementation, and only 11.5% had received iron from a government source. Children who had received iron were more likely to be male, from wealthier families, and have mothers who had received iron. We found that measuring haemoglobin was not useful for identifying iron deficiency in this population. The second study investigated serum hepcidin as a new diagnostic test of iron deficiency. As this assay could not be performed using the Indian samples, this study was performed in a prospectively recruited sample of 261 adult Australian female blood donors. The AUCROC for hepcidin compared with the transferrin receptorferritin index was 0.89. A reference range for hepcidin and clinically useful cut-offs to diagnose iron deficiency were determined. Our findings suggest that improving iron intake is essential to alleviation of anaemia in this population, but that current policies are being inadequately implemented. Equitable delivery of iron, strategies that improve maternal haemoglobin, and efforts to reduce poverty and improve food security may help control the burden of anaemia among Indian children.