This issue of Pediatric Clinics offers an update on Nutritional Deficiencies. Guest Editors Drs. Praveen Goday and Timothy Sentongo have assembled a panel of world-class experts who offer reviews on topics including Protein-energy malnutrition, Nutritional deficiencies in the developing world, Nutritional deficiencies in children on restricted diets, Nutritional deficiencies in obesity (including bariatric surgery), Nutritional deficiencies during normal growth, Nutritional deficiencies during critical illness, Nutritional deficiencies in preterm infants, Nutritional deficiencies in liver disease, Short bowel syndrome, Cystic fibrosis, Refeeding syndrome, and Therapies associated with nutrient deficiencies (Sulfasalazine, methotrexate, seizure medications, steroids).