ABSTRACT: BACKGROUND:Singing is a multimodal activity that requires physical, cognitive and psychosocial performance, with benefits to various domains of well-being and health in older adults. In recent years, research has increasingly studied group singing as an important cost-effective intervention to promote active and healthy aging. However, the specific factors responsible for these benefits need further experimental support, as most studies do not allow for causal inferences. This study responds to the need for further randomized controlled trials (RCT), with follow-up measurement, on the benefits of group singing in older adults from a low socioeconomic background. Also, while most studies often focus on specific outcome measure dimensions, in this study, the conjoint effect of several physical, psychosocial, psychoemotional and cognitive dimensions are analyzed, testing mediation effects of psychosocial and psychoemotional variables on the well-being and health of the participants. METHODS:We implement and measure the effects of a singing group program for older adults, with an RCT crossover design study, in a natural context, before and after the intervention and in a follow-up, 6 months after the intervention. PARTICIPANTS:140 retired older adults (>?60?years) users of a social support institution, will be invited to participate in a singing group program and randomly allocated to an experimental (n?=?70) and a control (n?=?70) group, which will enroll in the regular activities proposed by the institution. The intervention consists of 34 bi-weekly group singing sessions, of 2 h each, for 4 months. Measures on social and emotional well-being, cognitive function, and health indicators (e.g., blood pressure, glycemia, cholesterol, c-reactive protein, sedimentation rate, respiratory function, body balance, sleep quality, medication intake, and health services attendance) will be collected. Interviews will be conducted on the motivation and perceived benefits of participation. DISCUSSION:Significant improvements are expected in the outcome measures in the experimental group after the intervention, validating singing groups as a cost-effective intervention for healthy aging. Psychosocial and psychoemotional variables are expected to be mediators of the effects of the program in the cognitive function, well-being and health of the participants. TRIAL REGISTRATION:NCT03985917 . Registered 14th June 2019 (retrospectively registered).