The accurate diagnosis and subsequent treatment of malnutrition is an essential component of nutrition care because of the known negative impacts of malnutrition on patient outcomes. The detection of malnutrition is influenced by disease-specific characteristics, practice settings, and the availability of resources. This article explores how malnutrition diagnosis through the application of the Global Leadership Initiative on Malnutrition global consensus on malnutrition diagnostic criteria is impacted by the unique characteristics of the heart failure, oncology, and trauma populations. (Nutr Clin Pract. 2020;35:85-97)