Prolonged grief disorder (PGD) is a new mental health disorder introduced in 2018 to the International Classification of Diseases (ICD-11). These disorder guidelines reflect a new wave of interest in the global applicability of mental disorders. However, the operationalization of these criteria in different cultural contexts has yet to be determined. Additionally, the identification of culturally specific symptoms of grief with a valid and clinically acceptable questionnaire has yet to be established. This presentation will outline a research programme that aims to evaluate and improve the clinical utility of the ICD-11 PGD guidelines. This programme has two main phases. 1) Phase 1 involves bottom-up qualitative data to explore the anticipated challenges implementing the ICD-11 PGD. We developed a multi-level qualitative approach using semi-structured interviews with 48 key informants from Switzerland, China, Japan and Syrian refugees in Switzerland. We identified culturally specific grief beliefs that will directly inform the acceptability and usability of the new ICD-11 PGD guidelines. 2) Phase 2 involves psychometric validation and cross-cultural validation of a new culturally adaptable scale for ICD-11 prolonged grief disorder. Building on the findings from the qualitative interviews there were several empirical questions that emerged regarding the validity of the PGD diagnosis. The first step in resolving these challenges is developing a robust and validated scale.