Abstract: In December 1966, the city of Macau erupted in mass protests and rioting targeted at buildings and symbols of Portuguese rule—unrest that was countered by military force that left eight residents dead, hundreds wounded, and dozens in jail. In the aftermath of the violence, protests continued, as community leaders used Cultural Revolution rhetoric and tactics to try to force the Portuguese administration to accede to a series of escalating demands that included a written apology for its “crimes.” As the Macau governor tried to convince Lisbon to allow him to compromise, China’s central government and the Guangdong province government got involved, local residents refused to sell food to Portuguese residents, and thousands of Red Guards over the border in Guangdong province seemed poised to invade. This Macau version of Cultural Revolution ended with a historic scene: the Portuguese governor of Macau sitting at a table under an enormous portrait, signing a written apology to all Chinese residents of Macau, agreeing to close all of Kuomintang (KMT) agencies in Macau, and surrendering custody of seven KMT “spies” to mainland China. Through archival materials, newspaper reports and in-depth interviews, this article argues that the Macau 123 Incident was not simply a spillover of Cultural Revolution radicalism, but combined anti-colonial political grievances, anti-KMT political action, and Cultural Revolution-style political rhetoric and tactics.