On 17 November 2011, the United Nations General Assembly adopted a resolution (A/RES/66/170) designating 11 October as the first International Day of the Girl Child choosing ending child marriages as the theme of the day. Child marriage is a fundamental human rights violation and impacts all aspects of a girl's life. These marriages deny a girl of her childhood, disrupts her education, limits her opportunities, increases her risk of violence and abuse, and jeopardizes her health. The article presents data about the prevalence and effects, contributing factors and recommends action for prevention.