The Yale-Brown Obsessive-Compulsive Scale modified for Body Dysmorphic Disorder (BDD-YBOCS) is a semi-structured interview designed to assess the severity of current BDD. The aim of the study was to examine the factor structure and construct validity of the BDD-YBOCS. The sample included 366 adults with BDD who completed the BDD-YBOCS and other measures of BDD severity/impairment, psychiatric distress (i.e., anxiety and depression) and quality of life. Exploratory factor analysis supported two factors that were weakly correlated with each other ( r = .21): (1) Severity (i.e., time, distress, interference, and avoidance; 31.6% of the variance) and (2) Resistance/Control (i.e., reduced effort to resist symptoms and lack of control over symptoms; 16.7% of the variance). The Severity factor had good internal consistency ( α = .82) and good construct validity ( rs = .69-.81 with BDD severity/impairment; rs =.38-.56 with depression and anxiety; and rs = .48-.53 with functional impairment and quality of life). The Resistance/Control factor had acceptable internal consistency ( α = .74) but more limited construct validity ( rs = .27-.28 with BDD severity/impairment ( rs = .04-.20 with depression and anxiety and rs = .05-.14 with functional impairment and quality of life. Implications for the conceptualization and assessment of BDD severity are discussed., Competing Interests: Declaration of interests The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Drs. Snorrason and Jaroszewski have received salary support from Koa Health (formerly Telefónica Alpha, Inc). Dr. Greenberg has received salary support from Koa Health (formerly Telefónica Alpha, Inc) and is a presenter for the Massachusetts General Hospital Psychiatry Academy in educational programs supported through independent medical education grants from pharmaceutical companies. Dr. Snorrason has received salary support from Koa Health. Dr. Weingarden receives salary support from Koa Health (formerly Telefónica Alpha, Inc) and is a presenter for the Massachusetts General Hospital Psychiatry Academy in educational programs supported through independent medical education grants from pharmaceutical companies. Additionally, Dr. Weingarden has a consulting agreement with Hello Therapeutics, Inc. Dr. Phillips has received royalties/honoraria (past 12 months) from Oxford University Press (author, royalties), International Creative Management, Inc. (author, royalties), UpToDate/Wolter’s Kluwer (author, royalties), Guilford Publications (author, royalties), American Psychiatric Association Publishing (author, royalties), Merck Manual (author, honorarium), nView Health (scale developer, honorarium), OCD Scales (scale developer, honorarium), Simple and Practical Medical Education (author, honorarium), Informa Exhibitions (speaker at Miami Cosmetic Surgery and Aesthetic Dermatology Conference, honorarium), L’Oreal (presentation for Medscape, honorarium), Academic institutions and professional societies (speaker, honorarium). Dr. Hollander EH has received research grants from the Department of Defense, Food and Drug Administration, GW Pharma, and F. Hoffmann-La Roche Ltd; and editorial stipends from Elsevier; and served on scientific advisory boards for GW Pharma and F. Hoffmann-La Roche Ltd. RJ’s institution received payments for clinical trial agreements from Roche Translational & Clinical Research Center, Inc. and Genentech, Inc. Dr. Goodman receives royalties from Nview, LLC and OCDscales, LLC. Dr. Wilhelm is a presenter for the Massachusetts General Hospital Psychiatry Academy in educational programs supported through independent medical education grants from pharmaceutical companies; she has received royalties from Elsevier Publications, Guilford Publications, New Harbinger Publications, Springer, and Oxford University Press. Dr. Wilhelm has also received speaking honoraria from various academic institutions and foundations, including the International Obsessive Compulsive Disorder Foundation, the Tourette Association of America and the Centers for Disease Control and Prevention. In addition, she received payment from the Association for Behavioral and Cognitive Therapies for her role as Associate Editor for the Behavior Therapy journal, as well as from John Wiley & Sons, Inc. for her role as Associate Editor on the journal Depression & Anxiety. Dr. Wilhelm has also received honoraria from One-Mind for her role in Psy¬berGuide Scientific Advisory Board. Dr. Wilhelm is also on the Scientific Advisory Board for Koa Health, Inc. and for Noom, Inc. Dr. Wilhelm has received research and salary support from Koa Health, Inc. Additionally, Dr. Wilhelm has a consulting agreement with Noom, Inc. The other authors have no disclosures.