Context. Family carers need to be supported in their central role of caring for patients at the end of life, but brief practical tools to assess their support needs have been missing. To address this gap, we developed a brief evidence-based Carer Support Needs Assessment Tool (CSNAT) suitable for everyday practice. Objectives. To assess face, content, and criterion validity of the CSNAT and measure sensitivity to change over time. Methods. Participants were 225 adult carers of patients from six U. K. Hospice Home Care services.