The International Classification of Diseases Eleventh Edition (ICD-11), and the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), now include prolonged grief disorder (PGD). Since criteria for PGD in both classification systems differ from prior proposed grief disorders and each other, the validation of a single instrument to screen for prolonged grief (PG) symptoms of both new diagnoses is critical for bereavement research and care.