The process of nutritional assessment is a unique process that can be complex due to the interaction between physiological, pathological, and psychosocial factors. It is important to gather a wide range of information like dietary and medical histories, anthropometric measures, and estimates of energy requirements, which will allow the team of health care professionals to best help individuals. This chapter will provide the basis of “why” the comprehensive data must be required. Additionally, a discussion about body composition or shape and health outcomes will be highlighted as these can be key indicators of an individual’s health status. Nutritional needs will vary dramatically, and there is no single test that will fit all populations. The nutritional assessment is an ongoing process that the individual and health care professionals can continually assess for the best individual outcomes.