Ferré-Grau C, et al. - Researchers report a study protocol for a randomized and controlled analysis comparing the efficacy of a smartphone app-based intervention to increase positive mental health and decrease caregiver’s burden vs a regular intervention of caregivers in primary health care institutions. This investigation includes an experimental group and a control group. Participants include caregivers (n=108, over 18) with at least 4 months of experience as caregivers. A smartphone app that offers a daily activity (Monday-Friday) is installed by each caregiver and is used for 28 days. These activities are associated with the Decalogue of Positive Mental Health, designed ad hoc by a group of specialists. The score of caregiver burden, the positive mental health and participant satisfaction will be assessed as outcomes, following the first, third and sixth month. Via this investigation, evidence will be generated for the efficacy of an intervention using a free smartphone app. If proved as effective, with acceptable outcomes, then it could result in a reconsidering of the intervention extended to caregivers in primary care.