Adequate intake and assimilation of all nutrients is important for brain health and function; however, several nutrients have more marked effects on brain development. Based on the timing, the extent of deprivation, and the pathophysiology of a given nutrient, specific hypothesis can be made regarding the effects of a given nutrient on specific neural systems. Internationally adopted children present a unique opportunity to study the effects of early nutrient deficiencies on neurodevelopment under relatively controlled conditions, given that the time of adoption into a stable environment clearly demarcates the end of a period of adversity. Although micronutrient deficiencies have an adverse impact on development in other populations, little is known about the nutritional status at arrival or the role of nutritional status in neurodevelopment in international adoptees, a population in which some neurobehavioral problems persist years after adoption. The goals of this set of studies were to investigate (1) the macro- and micronutritional status of internationally adopted children and (2) the association between nutritional status and neurodevelopment during the early adoption period. Studies one and two investigated iron status in children adopted from Eastern Europe. In study one, international adoptees had compromised iron status, with iron deficiency more prevalent in participants with G. lamblia, a parasite which may interfere with iron absorption. There was persistent iron deficiency at follow-up, likely due to the erythropoietic demands of catch-up growth. In study two, iron deficiency was associated with general cognitive and behavioral development during the early adoption period. Specifically, those with iron deficiency were more fearful at arrival and had problems with activity and cooperation at the six-month follow-up. Cognitive performance was likely mediated by behaviors during testing. In study three, a comprehensive nutritional battery was completed for children adopted from Eastern Europe, Ethiopia, and China. 56% of the children had at least one micronutrient deficiency, with iron, zinc and vitamin D insufficiency/deficiency the most common deficiencies. Iron deficiency was associated with lower cognitive scores, slower speed of processing, as well as altered socioemotional behaviors and altered parent behaviors. Zinc deficiency was associated with lower quality exploratory behaviors and altered parent behaviors. These studies show that internationally adopted children are at risk for micronutrient deficiencies and that micronutrient status is associated with neurodevelopment during the early adoption period. Continued research will be important to understand the effects of these nutritional deficiencies on specific neurodevelopmental domains, to determine whether the developmental effects persist long-term, and to inform nutritional and neurodevelopmental principles that can be applied to develop interventions and services for children living in adverse and rehabilitating environments.