In 1981, The General Assembly of the United Nations proclaimed that the opening day of its regular session in September would be "officially proclaimed and observed as an International Day of Peace, dedicated to commemorating and strengthening the ideals of peace every nation and every people and among themselves.” The UN did this through resolution 36/67, which observed that day as a day of ceasefire and nonviolence worldwide, so that all nations and peoples are motivated to honour a cessation of hostilities throughout the day.

Later in 2001, through resolution 55/282 it established the International Day of Peace would be 21st September every year, "a date to be brought to the attention of all people for the celebration and observance of peace."
For the year 2010 the theme chosen by the Secretary-General Ban Ki-moon is Peace = Future. It's a way to emphasize the importance of youth and development in the world. "Young people are already playing a crucial role in the quest for peace. However, I know they can do even more. Therefore, this International Day comes with a challenge to young people everywhere develop their work to build peace. Share your plans and ideas, with creativity and passion. The concerns of the world will soon be in their hands, "said the Secretary-General.

This year's International Day of Peace coincided with a major summit on the Millennium Development Goals, the biggest campaign against poverty in the world. The summit brought together leaders from around the world at the United Nations from 20 to 22 September.

The Letter of Peace to the UN Foundation supports with this celebration, and as it has expressed in several different deliveries to the UN "expects that each of the member countries continue the journey towards peace using the methods and evidence proposed by the Letter of Peace."