The March 1st Movement, also known as the Sam-il (3-1) Movement (Hangul: 삼일 운동; Hanja: 三一 運動), was a protest movement by Korean people and students calling for independence from Japan, and protesting forced assimilation into the Japanese way of life. Thirty-three Korean cultural and religious leaders issued a proclamation, supported by thousands of students and civilians in Seoul. There were over 1000 demonstrations in many other cities. They were brutally suppressed, with Korean historian Park Eun-sik reporting about 7,500 killed and 16,000 wounded, and 46,000 arrested. These were among the earliest public displays of Korean resistance during the rule of Korea by Japan from 1910 to 1945. The event occurred on March 1, 1919, hence the movement's name, literally meaning "Three-One Movement" or "March First Movement" in Korean. It is also sometimes referred to as the Man-se Demonstrations (Korean: 만세운동; Hanja: 萬歲運動; RR: Manse Undong).

Today, March 1st is celebrated as a national holiday in the Republic of Korea (South Korea).