Why would countries that had long resisted the efforts against archaeological plunder reverse course and join these efforts?  The article solves this puzzle by examining the American and British decisions to join the 1970 UNESCO Convention.  Initially skeptical of UNESCO's endeavors, the United States and Britain changed their policies and came to support the international efforts in the early 1970s and early 2000s, respectively.  I argue that the two countries' policy shifts had similar causes.  First, archaeologists advocacy made policymakers aware of the damage caused by the illicit antiquities trade and the art world's complicity.  Second, public scandals exposed unethical behavior in the American and British art markets and demonstrated the need for regulation.  Third, the U. S. and British governments established domestic consensus in favor of regulation through advisory panels that included the major stakeholders: archaeologists, dealers, and museums.  Yet because of divergent bureaucratic attitudes, the U. S. government has ultimately been more vigorous in its efforts against the illicit antiquities trade than has the British government.