Peanut allergy is typically lifelong, often severe, and potentially fatal. Because reactions can occur from small amounts, the allergy presents patients with significant obstacles to avoid allergic reactions. In North America and the United Kingdom, prevalence rates among schoolchildren are now in excess of 1%, framing an increasing public health concern and raising research questions about environmental, immunologic, and genetic factors that may influence outcomes of peanut allergy. This review focuses on recent observations that continue to question the influences of maternal and infant diet on outcomes of peanut allergy, and explore how peanut may be uniquely suited to induce an allergic response. We highlight studies that affect current diagnosis, management, and the nature of advice that can be provided to patients, including the utility of diagnostic tests, doses that elicit reactions, characteristics of reactions from exposure, issues of cross-reactivity, concerns about peanut contamination of manufactured goods, and the natural course of the allergy. Clinical, molecular, and immunologic advances are reviewed, highlighting research discoveries that influence strategies for improved diagnosis, prevention, and treatment. Among the therapeutic strategies reviewed are sublingual and oral immunotherapy, anti-IgE, Chinese herbal medicine, and vaccine strategies.