Objectives: Dementia caregivers (CGs) are at heightened risk for developing problems with anxiety and depression. Much attention has been directed toward developing and deploying interventions designed to protect CG health, but few have been supported by rigorous empirical evidence. Technology-based interventions that are effective, scalable, and do not add greatly to the CG burden are of particular interest. Methods: We conducted a nine-month randomized controlled trial in 63 homes evaluating People Power Caregiver (PPCg), a system of sensors in the home connected to cloud-based software that alerts CGs about worrisome deviations from normal patterns (e.g., falls, wandering). Results: CGs in the active condition had significantly less anxiety than those in the control condition at the six-month assessment. Greater anxiety reduction in the active condition at the six-month assessment was associated with greater interaction with PPCg via SMS text messages. There were no differences in anxiety at the three-month or nine-month assessments or in depression at any assessment. Conclusions: PPCg shows promise for reducing anxiety associated with caring for a =person with dementia. Clinical implications: Technology-based interventions can help reduce CG anxiety, a major adverse consequence of caregiving that may be difficult to treat due to other demands on caregiver time and energy.