What explains the social reintegration of ex-combatants from armed conflicts? Community-level programs to reintegrate ex-combatants into society are based on the theory that the participation of ex-combatants in their communities can promote reconciliation and minimize recidivism to illegal activities. We evaluate community and security-related opportunities for and constraints on social reintegration using a survey of ex-combatants from Colombia. We find that ex-combatants in more participatory communities tend to have an easier time with social reintegration and feel less of a need to organize among themselves. These findings suggest that to help ex-combatants, reintegration processes should also work to improve the social vibrancy of receptor communities.