Updated project metadata. The extracellular matrix (ECM) is a master regulator of cellular phenotype and behavior. It plays a critical role in both normal tissue homeostasis and disease pathology. We have developed a fast and efficient approach to enhance the study of ECM composition and structure. Termed In Situ Decellularization of Tissues (ISDoT), it allows whole organs to be decellularized leaving native ECM architecture intact. We demonstrate how our approach enriches for ECM components allowing deep quantitative proteomic interrogation of the ECM. Using the ISDoT procedure, native ECM under normal and pathological conditions can be catalogued in unprecedented detail.