This chapter explores the phenomenon of social isolation, focusing on its defining characteristics, prevalence across populations, and its association with various psychopathological conditions, including depression, anxiety, and psychotic symptoms. Drawing on recent empirical findings, we highlight how social isolation has emerged as a significant public health concern, particularly in vulnerable and underserved groups. We then introduce a telematic psychotherapeutic intervention developed by our research group, designed specifically for adults experiencing chronic social isolation, who face barriers in accessing traditional, face-to-face mental health care through national health systems. The intervention leverages digital platforms to provide structured psychological support remotely. Finally, we present preliminary findings from an ongoing randomized controlled trial conducted at our laboratory and affiliated research center in Italy, aimed at assessing the clinical efficacy and feasibility of such intervention. These findings offer early insights into the potential of digital treatments to bridge existing gaps in mental health service provision.