We experimentally evaluate a novel approach to IPV prevention that harnesses social media to recruit and engage men in a virtual support group delivered by trained male facilitators via WhatsApp. The program succeeded in recruiting men at high risk of committing IPV through self-targeting alone: 52% of partners of men who enroll in the program in response to social media ads report experiencing IPV at baseline, more than four times the national average and nearly twice the rates observed in men recruited through targeted and untargeted invitations. Moreover, on average, participation in the program reduced the probability that female partners report sexual violence at endline by 20%. Treatment effects are concentrated among younger men (-36%), men who exhibit violence at baseline (-27%), and among those whose wives report that they do not drink alcohol (-40%). Program effects are also highly sensitive to group composition, which was randomly assigned. Segregating individuals based on baseline risk appears to magnify program impacts on high-risk individuals, and hence the program impact overall.