Objective To develop a new measurement system, the Traumatic Brain Injury Caregiver Quality of Life (TBI-CareQOL), that can evaluate both general and caregiving-specific aspects of health-related quality of life (HRQOL) in caregivers of persons with traumatic brain injury (TBI). Design New item pools were developed and refined using literature reviews, qualitative data from focus groups, and cognitive debriefing with caregivers of civilians and service members/veterans with TBI, as well as expert review, reading level assessment, and translatability review; existing item banks and new item pools were assessed using an online data capture system. Exploratory and confirmatory factor analysis, item response theory, and differential item functioning analyses were utilized to develop new caregiver-specific item banks. Known-groups validity was examined using a series of independent samples t tests comparing caregivers of low-functioning vs high-functioning persons with TBI for each of the new measures, as well as for 10 existing Patient-Reported Outcomes Measurement Information System (PROMIS) measures. Setting Three TBI Model Systems rehabilitation hospitals, an academic medical center, and a military medical treatment facility. Participants Caregivers (N=560) of civilians (n=344) or service members/veterans with TBI (n=216). Interventions Not applicable. Main Outcome Measures The TBI-CareQOL measurement system (including 5 new measures and 10 existing PROMIS measures). Results Exploratory and confirmatory factor analysis, item response theory, and differential item functioning analyses supported the development of 5 new item banks for Feelings of Loss-Self, Feelings of Loss-Person with TBI, Caregiver-Specific Anxiety, Feeling Trapped, and Caregiver Strain. In support of validity, individuals who were caring for low-functioning persons with TBI had significantly worse HRQOL than caregivers that were caring for high-functioning persons with TBI for both the new caregiver-specific HRQOL measures, and for the 10 existing PROMIS measures. Conclusions The TBI-CareQOL includes both validated PROMIS measures and newly developed caregiver-specific measures. Together, these generic and specific measures provide a comprehensive assessment of HRQOL for caregivers of civilians and service members/veterans with TBI. Highlights • The TBI-CareQOL measurement system includes new and existing self-report measures. • Measures were developed specific to caring for someone with traumatic brain injury. • Generic measures also evaluate important quality of life constructs for caregivers.