Social fragmentation and mental distress created by adverse environments are not new, nor are they limited to COVID-19.1Gross social injustices or armed conflicts have provoked widespread mental suffering, broken down social norms, and undermined social cohesion since time immemorial. Generations grow up in the midst of violence, normalizing it, or losing capacity to trust others or their institutions. Neglecting the psychosocial impacts of social injustices and violence on the individual and society undermines other efforts to build peaceful societies. Nevertheless, the use of mental health and psychosocial support (MHPSS)approachestobuild peace or prevent violent conflictremains anecdotal andad hoc. This document summarizes the existing arguments for why MHPSS should be more systematically used to sustain peace, and it offers some ideas for discussion on how to do this concretely through the UN system.