Over the span of his career, A. Roberto Frisancho has been one of the prime architects of the development and expansion of human population biology. His research and scholarly publications have helped to move the field beyond simple descriptions of human variation to address the nature and evolutionary origins of human biological diversity. Frisancho's early work in the Peruvian Andes elegantly demonstrated the importance of developmental acclimatization for promoting adaptive responses to the multiple stressors of high-altitude environments. Since mid-1970s, he has played a major role in developing and expanding the use of anthropometric techniques for assessing physical growth and nutritional status. Frisancho's influential publications have helped to make the use of anthropometric methods commonplace in the fields of nutritional science and public health. Throughout his career, Frisancho's work has examined how environmental, genetic, and developmental factors interact to influence human health and nutritional status. His research has addressed topics ranging from the determinants of low-birth weight infants in teenage mothers to the origins of obesity and associated metabolic diseases in populations of the developing world. Both the breadth and impact of Frisancho's work have been truly remarkable. The field of human population biology owes much to the tremendous contributions of A. Roberto Frisancho. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc.