This issue of Critical Care Clinics, guest edited by Dr. Mitchell M. Levy, focuses on Biomarkers in Critical Care. This is one of four issues each year selected by the series consulting editor, Dr. John Kellum. Articles in this issue include, but are not limited to: The History of Biomarkers; Biomarkers for Identifying Infection; Procalcitonin: Where Are We Now?; Soluble TREM-1: Diagnosis or Prognosis?; Lubricin as a Biomarker in Sepsis; Check Point Inhibitors and Their Role in Immunosuppression in Sepsis; Metabolomics and the Microbiome as Biomarkers in Sepsis; Lactate: Where Are We Now?; Predicting Renal Dysfunction; Biomarkers in the Evolution of ARDS; Biomarkers and RV Dysfunction; Biomarkers and Precision Medicine: State of the Art; The Use of Biomarkers for Population Homogeneity in Clinical Trials; and The Future of Biomarkers.