Book excerpt: A revised and updated version of the definitive peanut allergy book. Since the publication of The Peanut Allergy Answer Book in May 2001, there has been much additional research published in the field of peanut allergy and anaphylaxis in medical literature. This research includes new diagnostic tests, new vaccines and therapies, and new information on the history of peanut allergy. In addition, there has also been a great increase in public awareness of the societal impact of peanut allergy, such as in schools and other child-care facilities, in restaurants, and in the food and restaurant industry. This attention has led to the publication of guidelines for schools in the management of food allergies and anaphylaxis, to legislation such as the Food Allergen Labeling Consumer Protection Act of 2006, and proposed legislation for restaurant guidelines for food-allergic consumers. The incidence of peanut allergy has doubled in the past five years and continues to increase so the impact of this medical problem, particularly in young children, is enormous. The Peanut Allergy Answer Book, 2nd Edition,. contains 50% of new and revised material, including a new foreword and introduction, as well as new chapters such as, "Why has peanut allergy increased so much in the past 5-10 years?"; "What is the difference between being peanut-sensitive and peanut-allergic?"; "What is the Hygiene Hypothesis?"; and "Can skin contact cause an anaphylactic reaction?"