World Lymphoma Awareness Day is observed on September 15 since 2004. This day was was established by the Lymphoma Coalition, that is a non-profit network organization of 49 lymphoma patient groups around the world.
People of Mexico annually observe Cry of Dolores (Grito de Dolores) on September 15 to commemorate the event that marked the beginning of the Mexican War of Independence against Spain in 1810. In fact celebration of Cry of Dolores is a prelude to Independence Day.
International Day of Democracy is observed by the countries around the world on September 15. This observance is one of the UN International Days and it was established in 2007.
Free Money Day is a global event held annually on September 15. It is a social experiment that aims to promote economics based on sharing. The event was launched in 2011 by Post Growth Institute, an international group that explores paths to global prosperity that do not rely on economic growth.