T1 mapping using cardiovascular magnetic resonance (CMR) introduces novel techniques for myocardial tissue characterization to detect and quantify disease processes occurring at the microscopic level. Even though T1 mapping has limited spatial resolution, cellular and molecular changes occurring within each voxel can affect the aggregate T1 signal rendering them quantifiable. The estimated T1-based parameters quantified on a “map” demonstrate the spatial localization of these changes whereby each pixel expresses the quantitative value of that parameter. This quantification permits detection of diffuse disease even if it is not directly visible. Rather than relying on nonspecific functional measures, T1 mapping focuses on intrinsic changes of myocardial composition that advances understanding about specific disease pathways. These changes in myocardial tissue composition inform diagnosis and prognosis. T1 mapping encompasses two key parameters: native (i.e., precontrast) T1 and extracellular volume fraction (ECV) derived from additional postcontrast T1 and blood T1 measurements. These advances introduce new tools to detect focal and diffuse myocardial derangements occurring in cardiac disease that can be otherwise difficult to detect. T1 and ECV mapping foster precision medicine and personalized care, promising to improve patient outcomes through targeted therapy. Capitalizing on the opportunities introduced by T1 mapping and ECV requires further investigation.