The purpose of this study was to design and validate a family health assessment tool (FAMTOOL) based on a concept analysis of family and health. Preliminary testing of this instrument by a convenience sample of 80 adults resulted in an internal consistency coefficient of .90. A retest 2 weeks later produced a stability coefficient of .96. The FAMTOOL provides rehabilitation nurses with a quick, positive assessment instrument for helping patients and their family members assess their own family's health, compare responses with each other, and see strengths they might not have considered otherwise. As the family health system should be included in the initial assessment of everyone entering the healthcare system, the FAMTOOL may prove helpful to nurses in a wide variety of primary, secondary, and tertiary settings.