The International Children's Day had its origin in Turkey in 1920 (April 23, 1920) and later in the World Conference for the Well-being of Children in Geneva, Switzerland in 1925. It is not clear as to why June 1 was chosen as the International Children's Day: one theory has it that the Chinese consul-general in San Francisco (USA) gathered a number of Chinese orphans to celebrate the Dragon Boat Festival in 1925, which happened to be on June 1 that year. Also coincided with the conference in Geneva.
Children's Day was first celebrated worldwide in October 1955.