Functional status assessment has been recommended as a part of a complete nutrition assessment for decades, but the specific components of this assessment have eluded a consensus definition. The recent Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition consensus criteria for identification of malnutrition include functional assessment determined by handgrip dynamometry, with the understanding that this technique is not practical for use in some patient populations. Other techniques for functional assessment include physical performance measures such as timed gait and chair stands, as well as activities of daily living tools such as the Katz Index, Lawton Scale, and Karnofsky Scale Index. Manual muscle testing and computed tomography scan assessment of lean tissue are other tools that show promise in correlating functional and nutrition assessments. Functional assessment parameters may be least well correlated with nutrition status in older individuals. Despite a number of scientific studies of a variety of tools for functional assessment, there is to date no definitive tool for use in all individuals in all settings. Nutrition scientists and clinicians must continue to collaborate with colleagues in physical and occupational therapy, geriatrics, and nursing to refine current functional assessment tools to more effectively correlate with nutrition and malnutrition assessment parameters.