Introduction: When grief reactions after bereavement are so intense that they impair daily functioning, a diagnosis of disturbed grief may apply. Slightly differing criteria-sets for disturbed grief are included in the ICD-11, the DSM-5, and its forthcoming text revision, DSM-5-TR. We examined psychometric properties of a new self-report measure, the 22-item Traumatic Grief Inventory-Self Report Plus (TGI-SR+), that assesses these criteria sets for Persistent Complex Bereavement Disorder (PCBD) as per DSM-5, and Prolonged Grief Disorder (PGD) as defined in ICD-11 and DSM-5-TR. Material and methods: We examined the: i) factor structure, ii) internal consistency, iii) temporal stability, iv) convergent validity, v) known-groups validity, vi) probable caseness, and vii) optimal clinical cut-off scores in two Dutch bereaved samples. Sample 1 consisted of 278 adults, bereaved by various causes. Sample 2 included 270 adults who lost loved ones in a traffic accident. Results: We found support for a 3-factor PCBD model, 1-factor DSM-5-TR model, and 1-factor ICD-11 PGD model. The DSM-5 PCBD, DSM-5-TR PGD, and ICD-11 PGD items demonstrated good internal consistency and temporal stability. Associations between disturbed grief symptoms and posttraumatic stress and depression levels supported convergent validity. Associations between demographic/loss-related variables and disturbed grief symptoms supported known-groups validity. Optimal clinical cut-offs for the TGI-SR+ total score were ≥ 75, ≥71, and ≥ 75 for probable caseness of DSM-5 PCBD, DSM-5-TR PGD, and ICD-11 PGD, respectively. Discussion: While replication of our findings in diverse bereaved samples is needed, we conclude that the TGI-SR+ is a reliable and valid measure to assess symptoms of DSM-5 PCBD, DSM-5-TR PGD, and ICD-11 PGD.