In the western world, the prevalence of allergy and asthma has increased two- to threefold over the last 40 years and has reached epidemic proportions. This book represents the first complete document containing recommendations on the prevention of allergy and allergic asthma based on the current understanding of the immunological mechanisms of allergic reactions. Prevention of Allergy and Allergic Asthma was a collaborative project between the WAO (World Allergy Organization) and the WHO, launched in 1999. Following two interim reports, this monograph is the final report of the group of international experts involved in the project, ranging from basic immunologists to clinicians. Both theoretical and practical aspects are discussed, and constructive advice is given. Through its network of more than 70 member societies, the WAO will now promote the concept of prevention of allergies and allergic asthma worldwide to benefit patients prone to become allergic, to prevent the worsening of existing allergic diseases, and to reduce their high cost to society. This publication is recommended to specialists in allergy, pediatrics, pneumology and dermatology as well as to general practitioners, health care professionals, journalists, politicians and patients. Only by increasing the knowledge about allergic diseases throughout society can the right steps be taken for their effective prevention.