<p>The effects of malnutrition on psychological development and on structural and biochemical changes in the central nervous system are reviewed in both animals and humans. The evidence to date suggests that malnutrition has deleterious consequences for the developing organism and that the effects are most pronounced if not irreversible when nutritional insult is suffered during the period of rapid brain growth. Theoretical and methodological problems in the study of the relation between malnutrition and mental development are also discussed. The need for investigating the specific psychological and cognitive processes affected by malnutrition is pointed out and several research paradigms emphasizing the use of psycho-physiological techniques are suggested as a means of elucidating the relation between brain and behavior in the context of the problem of malnutrition and mental development.</p><p><em> </em></p>