The incidence of chronic gastrointestinal inflammatory diseases, including inflammatory bowel disease (IBD) and celiac disease (CeD) is increasing globally. IBD and CeD commonly develop in childhood and can have similar presentations, often exhibiting both gastrointestinal and extraintestinal manifestations. Inflammatory bowel disease and CeD have prevalence rates that vary according to race/ethnicity and geography. Both Crohn disease (CD; a type of IBD) and CeD affect nutrient and vitamin absorption because of their distribution in the small intestine. Thus, in both IBD and CeD, children are at risk for malnutrition and growth impairment. This chapter highlights the approaches and challenges to managing nutrition in patients with IBD and CeD.