Nutrition plays a fundamental role in determining the growth, development, and overall health of human beings. A child may experience growth deceleration if for any reason he becomes undernourished. In pediatric patients, poor nutritional status results in longer hospital stay, high medical expenses, and adverse clinical outcomes. Therefore, appropriate nutritional assessment is crucial for addressing nutritional needs and monitoring nutritional status in children. Physical examination provides important information on growth and development of children; body composition analysis gives a deeper insight into skeletomuscular health in children. Nutritional biomarkers via blood tests reflect not only nutrients storage but also metabolism and inflammation in the human body. More importantly, dietary intake needs to be investigated for eating patterns and behaviors, family environments, socioeconomic status, and psychology beyond. More importantly, dietary intake needs to be investigated for eating patterns and behaviors, family environments, socioeconomic status, and psychology behavior, and physical activities, screen time and sleep is strongly linked with overall health of children. This chapter describes methods for assessing and monitoring children’s nutritional status. It will emphasize the importance of regular nutritional assessment to improve health outcomes.