Military integration is intended to facilitate postconflict stabilization by creating unified armed forces from formerly antagonistic armed groups. However, integrated armies often struggle to overcome the factional identities of their soldiers, raising questions about interventionists’ ability to produce military cohesion during such processes. Yet, in the established scholarship on military cohesion, largely derived from the study of Western armed forces, internal small-group social dynamics are privileged over and above broader societal and political identities. This article examines the postconflict military integration program conducted in Sierra Leone to test extant theories of military “social cohesion.” Contrary to theoretical expectations, military cohesion in Sierra Leone proved highly reliant on wider (and highly politicized) societal identities, undermining integration efforts. This finding not only challenges existing understandings of social cohesion and its determinants but also the utility of military integration as a vehicle for postconflict stabilization and civil-military change.