Our concern with the study by Liu and colleagues is that it did not distinguish between the effects of chronic and acute malnutrition, the timing of the malnutrition, or the different forms of childhood malnutrition. Nutritional status was documented only at age 3; medical care before and after this age was not analyzed. It is well known that malnutrition during critical periods of brain development (from the second trimester of pregnancy to age 2) is associated with permanent deficits in brain and behavioral function, whereas malnutrition experienced after this period does not produce permanent deficits (6). Moreover, the authors were unable to eliminate the presence of continuing health and nutritional problems after age 3 as contributing to the observed behaviors. The definition of malnutrition used in this study is very unconventional. Heights and weights, standard measures of nutritional status, were not included despite a prior article by these authors that included heights and weights (7). Especially confusing is that the taller and heavier children (who were therefore presumably not malnourished) in their earlier study showed more aggression, conflicting with findings in the current study of more aggression in "malnourished" children. Finally, the term "dose-response," ordinarily used to describe quantitative differences on a single construct when the authors actually meant one or more comorbid conditions, was misleading.