Asthma has rapidly become one of the most common chronic illnesses of the Western world, and its prevalence continues to rise, with the proportion of patients with more severe diseases also increasing. Faced with this problem, more researchers are focusing on the causes, mechanisms, and pathophysiology of asthma. The major hopes are that more effective drugs will become available and that preventive measures can be instituted. Increasingly, molecular and cell bi- ogy approaches are being used to characterize and understand the mechanisms of the inflammatory process that is typical of the asthmatic airway. This volume on Asthma: Mechanisms and Protocols in the Methods in Molecular Medicineseries provides an overview of the molecular mechanisms involved in asthma by p- viding extensive protocols that are being used in asthma research. Briefly, it c- ers details of methods for obtaining cells from the airways, analysis of gene and protein expression in the limited clinical samples from asthmatic airways, use of molecular and cellular tools for studying cytokine expression and release, studies of asthma-related genes and genetic polymorphisms, and understanding the - fects of asthma treatments. With such coverage, the volume ties in several dis- plines, including allergy and immunology, cell biology, pharmacology, and histology. We have continued in the spirit of the series to provide a bench book for day-to-day use.