Advocacy is central to the work of preservationists, yet the particular set of issues that must be addressed when advocating for the preservation of Modern municipal buildings is a topic that has not been previously explored. In addition to the challenges commonly confronted when advocating for the preservation of postwar resources, monumental Modern municipal buildings face substantive obstacles that emanate exclusively from their municipal ownership. Challenges encountered firsthand in advocating for the preservation of the Philadelphia Police Administration Building (the Roundhouse) serve as the primary motivation for this study which investigates the determining factors that lead to the successful preservation of Modern municipally owned buildings. Through case studies on the advocacy efforts for Boston City Hall, the Los Angeles Police Facilities Building (Parker Center), and the Philadelphia Police Administration Building, this thesis presents a series of best practices for both grassroots and organizational preservation advocates. The established recommendations are the result of empirical evidence obtained through interviews with individuals presently advocating for the preservation of Modern municipal buildings, those involved with local and national preservation organizations, municipal staff, and scholars in the field of Modern architectural preservation. While theoretical in nature, the presented strategies serve as sound maneuvers for shaping strategic plans for future efforts.