This Practice Guidelines document has been co-published in Phlebology DOI: 10.1177/0268355521999559 and Journal of Vascular Surgery: Venous and Lymphatic Disorders DOI: 10.1016/j.jvsv.2020.12.084. The publications are identical except for minor stylistic and spelling differences in keeping with each journal’s style. The contribution has been published under a Attribution-Non Commercial 4.0 International (CC BY-NC 4.0), (https://creativecommons.org/licenses/by-nc/4.0/) With the support of the American College of Obstetricians and Gynecologists, the American Vein & Lymphatic Society, the American Venous Forum, the Canadian Society of Phlebology, the Cardiovascular and Interventional Radiology Society of Europe, the European Venous Forum, the International Pelvic Pain Society, the International Union of Phlebology, the Korean Society of Interventional Radiology, the Society of Interventional Radiology, and the Society for Vascular Surgery As the importance of pelvic venous disorders (PeVD) has been increasingly recognized, progress in the field has been limited by the lack of a valid and reliable classification instrument. Misleading historical nomenclature, such as the May-Thurner, pelvic congestion, and nutcracker syndromes, often fails to recognize the interrelationship of many pelvic symptoms and their underlying pathophysiology. Based on a perceived need, the American Vein and Lymphatic Society convened an international, multidisciplinary panel charged with the development of a discriminative classification instrument for PeVD. This instrument, the Symptoms-Varices-Pathophysiology (“SVP”) classification for PeVD, includes three domains—Symptoms (S), Varices (V), and Pathophysiology (P), with the pathophysiology domain encompassing the Anatomic (A), Hemodynamic (H), and Etiologic (E) features of the patient’s disease. An individual patient’s classification is designated as SVPA,H,E. For patients with pelvic origin lower extremity signs or symptoms, the SVP instrument is complementary to and should be used in conjunction with the Clinical-Etiologic-Anatomic-Physiologic (CEAP) classification. The SVP instrument accurately defines the diverse patient populations with PeVD, an important step in improving clinical decision making, developing disease-specific outcome measures and identifying homogenous patient populations for clinical trials.