This review highlights some of the research advances in anaphylaxis; hypersensitivity reactions to foods, drugs, and insects; and allergic skin diseases that were reported in the Journal in 2011. Food allergy appears to be increasing in prevalence and carries a strong economic burden. Risk factors can include dietary ones, such as deficiency of vitamin D and timing of complementary foods, and genetic factors, such as filaggrin loss-of-function mutations. Novel mechanisms underlying food allergy include the role of invariant natural killer T cells and influences of dietary components, such as isoflavones. Among numerous preclinical and clinical treatment studies, promising observations include the efficacy of sublingual and oral immunotherapy, a Chinese herbal remedy showing promising in vitro results, the potential immunotherapeutic effects of having children ingest foods with baked-in milk if they tolerate it, and the use of anti-IgE with or without concomitant immunotherapy. Studies of allergic skin diseases, anaphylaxis, and hypersensitivity to drugs and insect venom are elucidating cellular mechanisms, improved diagnostics, and potential targets for future treatment. The role of skin barrier abnormalities, as well as the modulatory effects of the innate and adaptive immune responses, are major areas of investigation.