This Special Issue of Diagnostics, titled "Advances in the Diagnosis and Management of Vasculitis," offers a global perspective on the rapidly evolving landscape of vascular inflammation. Featuring eleven expert contributions from researchers in Spain, Poland, the USA, Germany, Romania, and Turkey, the collection highlights the shift toward precision medicine and non-invasive diagnostic excellence. A central theme of this issue is the transformative role of modern imaging. From the critical review of 18 F-FDG-PET/CT in Polymyalgia Rheumatica to the use of transcranial duplex sonography for monitoring large-vessel involvement, these articles demonstrate how advanced technology is reducing the need for invasive biopsies while preventing devastating complications like ischemic stroke and irreversible vision loss. Beyond imaging, this issue delves into the complex immunopathogenesis of small-vessel vasculitis, exploring the crosstalk between neutrophils and platelets as a source for novel biomarkers. Clinical insights into rare conditions, such as DADA2 deficiency and Takayasu arteritis, are balanced by prospective studies on adult IgA vasculitis nephritis and the classification accuracy of IgG4-related disease, as well as a comprehensive review of giant cell arteritis. Together, these works emphasize a multi-disciplinary, patient-centric approach aimed at reducing glucocorticoid toxicity and optimizing long-term outcomes.