Recent studies of the effects of developmental iron deficiency (ID) and iron deficiency anemia in nonhuman primates have provided new insights into this widespread and well-recognized human nutritional deficiency. The rhesus monkey was the animal model in these experiments, which used extensive hematological and behavioral evaluations in addition to noninvasive brain measures. Two important findings were as follows: 1) different behavioral consequences depending on the timing of ID relative to brain developmental stages and 2) the potential for long-lasting changes in brain iron regulatory systems. Further work in this model, including integration with studies in humans and in laboratory rodents, is ongoing.