The aggregation and accumulation of pathologic forms of the microtubule-associated tau protein into fibrils, eventually forming characteristic tangle pathology, hallmarks the majority of all neurodegenerative disorders. These so-called tauopathies, of which Alzheimer’s disease (AD) is the most common form, are difficult to identify and diagnose, especially at early disease stages. However, a recently proposed research framework for the biological definition of AD called for the definition of tau pathology status, highlighting the need for highly specific tools to assess disease-related tau pathology [1]. While it has been possible to measure tau pathology in the cerebrospinal fluid (CSF) for decades [2], the relatively recent development of positron emission tomography (PET) ligands to visualize, map, and quantify tau pathology in the living brain has already provided substantial additional information about the temporal and spatial characteristics of tau aggregation during disease development, holding promise to serve as a highly valuable diagnostic tool to stage disease-related pathology [3]. This talk will describe the current state of tau biomarkers derived from neuroimaging with PET as well as their relationship with post mortem findings[4], fluid-derived biomarkers for tau pathology [5], and cognition [6]. Specifically, I will focus on the potential research and clinical applications of tau PET, as well as on potential stumbling blocks on the road ahead.