Length and weight data from a longitudinal study of rural Guatemalan subjects birth to 7 y of age and height and weight data from a cross-sectional study of the same subjects when they were 11-24.9 y old are compared to reference data for the USA general population and for Mexican-Americans. At birth, the median length of Guatemalan children is at approximately the 16th percentile of the USA reference or approximately 2 cm shorter. By 6 mo of age, Guatemalan children are shorter, on average, than the 5th percentile of the reference curves and, in absolute terms, are approximately 5 cm below the median; by 3 y, the difference increases to approximately 10 cm. As adults, Guatemalans have about the same absolute level of deficit (approximately 13 cm) as they did at age 3 y. If the general USA population is used for comparison, Guatemalans can be said to grow as expected during adolescence, neither recuperating the growth retardation of early childhood nor falling further behind in size. If the Mexican-American sample is selected instead, it would appear that some catch-up in growth occurs in Guatemalan adolescents. Regardless of the choice of reference population, growth is markedly retarded only in early childhood; adolescence is not a period when growth is significantly constrained.