The International Day of Peace, also known as the World Peace Day, occurs annually on 21 September. It is dedicated to peace, and specifically the absence of war, such as might be occasioned by a temporary ceasefire in a combat zone. It is observed by many nations, political groups, military groups, and peoples. The first year this holiday was celebrated was 1981.

To inaugurate the day, the "Peace Bell" is rung at UN Headquarters (in New York City). The bell is cast from coins donated by children from all continents apart from Africa. It was given as a gift by the United Nations Association of Japan, and is referred to as "a reminder of the human cost of war." The inscription on its side reads: "Long live absolute world peace."

Individuals can also wear White Peace Doves to commemorate the International Day of Peace, which are badges in the shape of a dove produced by a non-profit in Canada.

The United Nations General Assembly declared, in a resolution sponsored by the United Kingdom and Costa Rica, the third Tuesday of September/the opening day of regular sessions of the General Assembly as the International Day of Peace devoted to commemorating and strengthening the ideals of peace.