The Tangwai (黨外; pinyin: dăngwài; literally, "outside the party") movement was a political movement in the Republic of China on Taiwan in the mid-1970s and early 1980s. Although the Kuomintang had allowed contested elections for a small number of seats in Legislative Yuan, opposition parties were still forbidden. As a result, many opponents of the Kuomintang, officially classified as independents, ran and were elected as members outside the party. Because the majority of seats in the Legislative Yuan were held by delegates elected in 1947, pending the retaking of the Mainland, the Tangwai movement had no possibility of seizing power, but they were able to use the legislature as a forum for debating the ruling Kuomintang.

The members of the Tangwai movement formed the Democratic Progressive Party in 1986. Although still illegal, the KMT did not take action against the DPP and the party was legalized in 1991. Many current politicians in Taiwan, most notably President Chen Shui-bian and Vice President Annette Lu were active in the Tangwai movement.

These political phenomena see some parallel in the recent history of local contested elections in mainland China.

See also: Politics of Taiwan