 The goal of this proposal is to produce a new treatment that would benefit subjects who have peanut allergy by lowering the risk of anaphylactic reactions desensitization, and changing the peanut-specific immune response in subjects who have peanut allergy tolerance. This project is designed to study if peanut oral immunotherapy OIT will desensitize subjects with peanut hypersensitivity by regulating their oral and systemic immune reactivity and cause long-term tolerance. This study will augment other ongoing studies by looking at whether anti-IgE therapy can reduce side effects and allow for an accelerated build up phase. Peanut allergic patients greater than 12 years old will undergo omalizumab anti-IgE treatment for 4 months prior to peanut OIT, and they will continue omalizumab until one month after maintenance therapy. Each subject will have an initial desensitization phase over 2 days to a goal of 950 mg of peanut powder followed by a build up phase over 4 months to goal maintenance dose of 8000 mg peanut powder. They will be randomized to continue maintenance for 12 or 24 months. They will then have an oral food challenge OFC immediately after stopping peanut OIT to test for desensitization. Four weeks later, off OIT, another food challenge will be done to assess tolerance. Outcome variables of interest include results of the OFCs, pre and post skin tests, CAP-FEIA values and basophil studies. These results will be compared between the starting point and the patient at the end of the study using appropriate statistical analysis. 