This article analyses public discourse debating the legalization of commercial sex trade in Taiwan after the government announced the decision to deliberate towards the decriminalization of prostitutes in 2009. A multi-layered rhetorical model of function, strategy and form is applied to investigate the rhetorical structures of social campaign discourse from both pro-and anti-sides of the controversy. The public discourse examined includes NGO announcements, news releases, press coverage, letters to the editors, and town meeting reports, corroborated with other significant public discourse texts since 2004. The study concludes with an evaluation of how effective the rhetorical campaigns are in accordance with their respective goals and suggestions for those developing or revising advocacy plans for social changes.