The first chapter, entitled “Pathophysiology of Airway Inflammation in Asthma,” provides an overview of the epidemiology of asthma, integrating genetic and environmental influences as well as information on cellular inflammation. The succeeding chapters then outline specific cells, cellular components such as proteases and peroxidases, oxidative stressors, chemokines, cytokines, and other mediators that are important in airway inflammation. Several chapters are devoted to reactive nitrogen species and to the regulation of nitric oxide and its role in inflammation. Specific attention is paid to the contributions of interleukin (IL)-4, IL-13, and IL-5, which have long been known to be important in asthma pathogenesis, and to the prospects of directed therapy against these mediators. The cytokines IL-9, IL-16, and IL-18, often less commonly discussed in the context of airway inflammation in asthma, are also covered along with the potential that they, too, may hold for asthma treatment. The last seven chapters focus on the genetics of asthma, pharmacogenetic considerations that may impact the response to therapy, and recently developed treatments directed at a variety of other targets, including immunotherapy, peptide agents, and anti-IgE.