Caregiver burnout is a serious concern among informal caregivers, especially for those who provide care to individuals with more severe limitations such as power mobility users. The Power Wheelchair Caregiver Assistive Technology Outcome Measure tool measures device specific and overall burden experienced by informal caregivers of power mobility users. A one-month, test-retest study was conducted to examine the reliability, internal consistency, and construct validity of the Power Wheelchair Caregiver Assistive Technology Outcome Measure. Two construct validity measures were administered: the Hospital Anxiety and Depression Scale and the Late Life Disability Index. The test-retest-reliabilities of part 1 (power wheelchair specific burden) and part 2 (general caregiving burden) were 0.769 and 0.843 respectively. Scores on part 1 were moderately and positively correlated with part 2 and with frequency of participation. Scores on part 2 were moderately and negatively correlated with anxiety, depression, and positively with perceived limitation of participation. The strength and direction of these correlations provide support for the construct validity of the measure and suggest part 1 and part 2 provide complementary information. Further testing is needed to assess the clinical utility and responsiveness of the measure.