 Peanut allergy is known to cause severe anaphylactic reactions. Compared with other food allergies it tends to be more persistent and also its prevalence seems to be rising. Currently there is no proven treatment other than strict avoidance. We are attempting to decrease the risk of anaphylaxis on accidental ingestion by desensitizing subjects to peanut using peanut oral immunotherapy OIT. We are also studying the effect of peanut OIT on the peanut specific immune response to determine if tolerance to peanut protein will develop. Children ages one to six years of age with peanut allergy will be randomized to peanut OIT or placebo active subjects. Thirty subjects will also be recruited as controls. These subjects will not receive any peanut or placebo but only have skin prick testing and lab work in addition to a history and physical exam. Active subjects will undergo a modified rush immunotherapy on the first day and then increase the doses at least every two weeks up to a maintenance dose of 4 grams equivalent to about 13 peanuts. Doses will be taken daily at home except for dose increases which will be done on the research unit. Outcome variables of interest include response to double-blind placebo controlled food challenge, skin prick testing, peanut specific IgE, and adverse events. These results will be compared between the start and end of peanut OIT using appropriate statistical analysis. 