Objective: This study aims to develop and validate the stigma assessment tool for family member caregivers of patients with mental illness (SAT-FAM). Methods: This study was conducted in three phases: (1) explicate the concept of stigma towards family caregivers of patients with mental illness, (2) develop and iteratively optimise a preliminary version of the SAT-FAM, and (3) test the psychometric properties of the final version of the SAT-FAM.