In May 2017, Taiwan's Constitutional Court reached a landmark decision that marriage should be opened to same-sex couples within two years, making Taiwan potentially the first country in Asia to realize marriage equality. How can we explain the success of the LGBT movement here? I argue that explanations based on cultural proclivity, public opinion, and linkages to world society, are inadequate. This article adopts a “political process” explanation by looking at changes in the political context and how they facilitate the movement for marriage equality. I maintain that electoral system reform in 2008, the eruption of the Sunflower Movement in 2014, and the electoral victory of the Democratic Progressive Party in 2016, stimulated Taiwan's LGBT mobilization, allowing it to eventually overcome opposition from the church-based countermovement.