ABSTRACT: The benefits of mindfulness meditation among clinical and non-clinical populations have been largely reported in literature. Existing mindfulness-based programs are particularly useful in targeting specific populations while researchers have pointed out the possibility of developing programs adapted to the audience and the context. In this two-groups pre-post experimental design we developed a mindfulness-based social intervention program to target individuals from the general population. Here we present a two-groups pre-post experimental design to investigate its effectiveness on participants' psychological functioning assessed by eight self-reported questionnaires (CORE-OM, FFMQ, SWLS, PANAS, PSS, SCS, WEMWBS, SHS) which encompass different domains of well-being, mindfulness and emotional functioning. Participants, recruited on voluntary basis, were randomly allocated to treated or passive control groups and were aware of group allocation. The intervention comprises a 12-week meditation training in a big group that represents the social aspect of meditation. Data were analysed via a linear mixed effect model and intention to treat. Statistically significant results were obtained for global score of CORE-OM (? = -0.20 [-0.30; -0.10], p = 0.0002), FFMQ (? = 0.20 [0.12; -0.28], p < 0.0001), SWLS (? = 1.43 [0.42; 2.45], p = 0.006), positive PANAS (? = 1.99 [0.95; 3.04], p = 0.0002), negative PANAS (? = -1.67 [-2.92; -0.43], p = 0.009), PSS (? = -2.98 [-4.25; -1.71], p < 0.0001), WEMWBS (? = 4.38 [2.93; 5.83], p < 0.0001) and SHS (? = 1.43 [0.42; 2.45], p = 0.006). Our intervention is causally associated with an improvement of the psychological functioning and hence can be considered as a preventive measure that may potentially reduce the risk of developing psychological problems and improve the subject's general well-being. Given the voluntary recruitment, our inference only applies to those individuals who have decided to experience meditation as a way to well-being and not to a random person from the general population.