The consequences of psychiatric disorders for family members, usually called family or caregiver burden, have been studied during the last 4 decades. During this period a variety of instruments have been developed to measure the impact of mental illness on family members, but not all instruments have been described systematically in the published literature. The authors review 21 instruments that have been used or developed during the last 10 years, including several that have not previously been reported. The protocols are described in terms of their method and comprehensiveness, precursors and theoretical foundations, and types of psychometric information available. The instruments are assessed for potential use as research tools, and also for application in routine clinical practice.