Every year, throughout the world, millions of young girls are forced into marriage. Child marriage is outlawed in many countries and international agreements forbid the practice yet this tradition still spans continents, language, religion and caste.

Over an eight-year period, photographer Stephanie Sinclair has investigated the phenomenon of child marriage in India, Yemen, Afghanistan, Nepal and Ethiopia. Her multimedia presentation, produced in association with National Geographic, synthesizes this body of work into a call to action.

Stephanie Sinclair's images are featured in a story on child marriage in the June 2011 issue of National Geographic magazine.

How to help: National Geographic has compiled a list of organizations that encourage families to delay marriage and give girls an opportunity to reach their full potential.

In a related post Stephanie Sinclair shares the difficult experiences child brides face. She discusses the need for their voices to be heard and the challenges she faced as a journalist who witnessed their struggles and abuse.