Iron deficiency remains a major worldwide public health problem, especially in developing countries such as India. In this randomized study, 223 children aged 12-18 months from Mumbai, Maharashtra, India were fed either iron and zinc-biofortified pearl millet or control pearl millet three times per day, six days per week, for nine months. The goal of this study was to examine the effects of iron and zinc-biofortified millet on markers of iron status, growth, and immune function in this age group. The key outcome measures were biomarkers of iron status, physical growth, and immune function defined as response to measles vaccine. Concentrations of serum ferritin and hemoglobin as well as markers of immune function were assessed at enrollment (baseline), at an intermediate time point (midline; random serial sampling) and after 9 months of follow-up (endpoint). Additionally, we measured concentrations of C-reactive protein (CRP), as iron biomarkers can be influenced by inflammation. Growth was assessed monthly for 9 months and expressed as anthropometric Z-scores.