This chapter focuses on the effects of socioeconomic factors, infection, and diet on the physical growth of children in developing countries. The World Health Organization (WHO) recommends that growth charts prepared by the US National Center for Health Statistics (NCHS) be used for assessing the nutritional status of children from birth to 10 years of age in developing countries. 1 approach to the investigation of ethnic differences in body size is to compare the growth of healthy, well-nourished children of different ethnic origins. Data suggest that ethnic differences in growth potential are minor prior to puberty and that it is during this stage that major differentiation between ethnic groups takes place. However, within ethnic groups in developing countries, differences in body size between social classes are often very large. Researchers have also found that indicators of socioeconomic status, even within a certain class, are strong predictors of the body sizes of children. Land, actual food production by the family, and income are factors which predict body size. The length of children from developing countries is generally near the 15th percentile of the NCHS growth charts during the 1st few months of life. After a period of relative well-being in early infancy, nutritional status rapidly deteriorates, being worst in the 2nd year of life; the nutritional status of children does not seem to improve until later, in the 3rd or 4th year of life. The most important infection affecting young children in developing countries is diarrheal diseases. The diarrheal diseases are important determinants of poor growth and development in poor countries. Overall, an analysis of the magnitude of the differences between well-to-do children of various ethnic groups and the differences within ethnic groups that are associated with social class shows that the variation that can be attributed to environmental factors in developing countries far overshodows that which can e attributed to genetics. - See more at: http://www.popline.org/node/344869#sthash.K3Ffscrg.dpuf