Purpose: Despite its prevalence and negative consequences, research on elder abuse has rarely considered resident-to-resident aggression (RRA) in nursing homes. This study employed a qualitative event reconstruction methodology to identify the major forms of RRA that occur in nursing homes. Design and methods: Events of RRA were identified within a 2-week period in all units (n = 53) in nursing homes located in New York City. Narrative reconstructions were created for each event based on information from residents and staff who were involved as well as other sources. The event reconstructions were analyzed using qualitative methods to identify common features of RRA events. Results: Analysis of the 122 event reconstructions identified 13 major forms of RRA, grouped under five themes. The resulting framework demonstrated the heterogeneity of types of RRA, the importance of considering personal, environmental, and triggering factors, and the potential emotional and physical harm to residents. Implications: These results suggest the need for person-centered and environmental interventions to reduce RRA, as well as for further research on the topic.