This article investigates community development and social impacts of hosting an international sport event in a post-war city still marred by social divisions and internal conflict. Focusing on the case of Mostar, Bosnia and Herzegovina, this research examines resident perceptions of the recurrent Red Bull Cliff Diving World Series event. The framework of Sport for Development and Peace (SDP) guides this inquiry toward understanding how sport events can help facilitate greater unity and peace in transitional settings experiencing persistent social divisions. Qualitative data from semi-structured interviews with residents are supported by findings from a resident survey. The findings illustrate how sport events can help to transform communities in line with SDP goals by fostering spaces for social cohesion, generating collective pride, and offering new senses of possibility and opportunity for the city. These outcomes can occur even if the event organization is not explicitly driven by an SDP mission. Perceptions of trust and neutrality are important factors in how community members assess the event and its organizing body. This research highlights the role of international sport events in community development and calls attention to the importance of understanding local context and engaging a broad range of community members.