This issue of Clinics in Chest Medicine focuses on Acute Respiratory Distress Syndrome and covers topics such as: Epidemiology and Definitions of ARDS and Early Acute Lung Injury, Environmental Risk Factors for ARDS, Clinical and Biological Heterogeneity in ARDS: Direct vs. Indirect Lung Injury,Obesity and Nutrition, Important Immunomodulators in ARDS?, Beyond SNPs?Genetics, Genomics and Other Omic Approaches to ARDS, Clinical Approach to the Patient with ARDS, The Immunocompromised Patient with ARDS: Role of Invasive Diagnostic Strategies, Clinical Trial Design in Prevention and Treatment of ARDS, Beyond Low Tidal Volume?Ventilating the Patient with ARDS, Prone Positioning in ARDS, and more!