World Humanist Day is celebrated every year on June 21. It is an opportunity for Humanist individuals and organizations to publicize the positive values of Humanism and to share the global concerns of the Humanist movement.

Humanist groups have been celebrating World Humanist Day since the 1980s. It is the only freethought holiday officially recognized by the International Humanist and Ethical Union (IHEU), the global federation for Humanist, atheist, rationalist, ethical culture, secularist and other freethought groups.

Humanist groups around the world mark World Humanist Day with a wide variety of activities ranging from activism to parties. World Humanist Day may be recognized with official proclamations or promotional campaigns to educate people about the size of the secular community and the ethical values of Humanists. Groups may run courses or conferences to deepen understanding of Humanist principles and programmes. They may emphasize their global solidarity by raising awareness and money for a freethought group working in a different country. Or groups may simply throw a party or share a picnic to celebrate their sense of community.