Implementing evidence-based and cost-effective bereavement care is a challenge. A self-report measure could assist to identify caregivers at-risk of prolonged grief. We developed a new measure via five steps: identification of risk and protective factors for prolonged grief, item generation, consultation with an expert panel (n = 8), review by the academic team and expert panel, and a pilot test with family caregivers (n = 19) from three palliative care services. The Grief and Bereavement Assessment is a brief self-report measure that is theoretically and empirically grounded, acceptable to caregivers, feasible for use in palliative care, and requires psychometric validation.