Definition CLASSIFICATION AND TYPOLOGY Although the diagnosis of "failure to thrive" (FTT) is made frequently, both the meaning of the term and its value as a diagnosis remain debatable. Because any serious disease can cause growth failure, the term FTT has little diagnostic usefulness. Classically, the etiology of FTT has been divided into organic and nonorganic types, with nonorganic FTT defined as growth deficiency without a diagnosable medical etiology and organic FTT defined as growth failure caused by a specific medical illness. A number of authors have questioned the adequacy of this dichotomous view, suggesting the need for a third category: "mixed" etiology. In this group of children, chronic, mild problems, such as recurrent otitis media in concert with behavioral problems, result in aberrant behaviors, such as difficult temperament, sleep disorders, and altered eating behavior, which together impair growth. Even in cases in which the growth deficiency is primarily due to organic or nonorganic causes, the problems seen in the children are often multiple (eg, infants who have cardiac failure also have feeding disorders). Given the multiple contributory factors to FTT and the lack of diagnostic specificity of the term, we recommend that it be abandoned in favor of the term "growth deficiency," which describes the presentation of this entity: An underweight, often stunted, undernourished child.