Food allergies are a major health problem in the US with an estimated 11 million Americans afflicted. Peanut allergy, which affects over 1.5 million Americans, is the single leading cause of severe and fatal food-induced allergic reactions. The prevalence of peanut allergy in children has doubled since the mid-1990's, and eosinophilic esophagitis (EE), largely food-related in children, has also markedly increased in prevalence. The current standard of care for managing food allergies consists of educating patients about food allergen avoidance and initiating therapy in case of an accidental ingestion. This approach is clearly inadequate since food allergic reactions are the leading single leading cause of anaphylaxis treated in US emergency departments, and dietary management of EE is extremely difficult and often ineffective. Recent oral immunotherapy trials suggest new approaches may alter the course of these disorders. A Consortium of investigators from five universities was formed to address this problem: Mount Sinai, Johns Hopkins, Duke, Arkansas, and National Jewish Health. The main objectives of this Consortium were to investigate the natural history of milk, egg and peanut allergy in infants, delineate underlying immunologic parameters associated with the natural course of milk and egg tolerance and peanut sensitization, and Identify biological markers that distinguish young children likely to develop symptomatic peanut allergy; and to test novel immunotherapies for the treatment of food allergy and delineate responsible mechanisms. The highly successful Consortium has recruited and retained a large cohort of children at high risk to develop peanut allergy, initiated three novel therapeutic trials, and been investigating immunologic mechanisms associated with the development and natural history of food allergy and immunotherapy. The Consortium proposed here will extend ongoing studies on the previous observational cohort and peanut SLIT trial, evaluate the efficacy of two novel immunotherapeutic approaches, and with the addition of a new site at Cincinatti Children's Hospital, initiate studies on the role of food allergy in EE, comparing and contrasting natural history and immunologic and genetic markers of EE with those of IgE-mediated food allergy.