Whether providing service for fire or emergency medical emergencies, the primary goal of a fire department is to provide the best possible service via the most effective and efficient manner. The ability to fulfill this internal promise can be extremely difficult when agencies collaborate. Mass casualty operations within Milwaukee County are dynamic and vary depending on the authority-having jurisdiction. The problem was that mass casualty operational procedures within Milwaukee County had not been compared and contrasted to determine the effectiveness of incident management and agency interoperability. The purpose of this research was to compare and contrast the mass casualty operational procedures of the fire departments within Milwaukee County to determine the effectiveness of incident management and agency interoperability. A descriptive research methodology was used to answer the following: (a) What components should a mass casualty operational procedure consist of? (b) How are the current mass casualty operational procedures within Milwaukee County similar? (c) How are the current mass casualty operational procedures within Milwaukee County different? (d) What modifications can be made to the mass casualty operational procedures to allow for more effective incident management and agency interoperability? Library and Internet research, combined with the results of a regional survey instrument and interviews conducted by the author, produced the results presented in this Applied Research Project (ARP). The results yielded an extreme need to develop a common operational guideline. The author developed recommendations, which include the establishment of a committee to develop a common operational guideline for adoption by each individual organization. Once adopted, the Milwaukee County Fire Training Officers could develop and conduct the training of all department personnel within each organization. Finally, dialogue should exist between the Milwaukee County Emergency Medical Services personnel and all area hospital employees to update all parties on the newly developed operational procedure.