The 31-year-old Grammy winner was in Ghana this week with Free the Slaves, a nonprofit organization whose mission is to "end slavery worldwide."
Mraz spent five days in the country, traveling with James Kofi Annan, a former child slave who used to work on fishing boats and had been enslaved for seven years.
Annan founded Challenging Heights, a school in Winneba where many of its students are former slaves. The children performed songs for Mraz.
The singer also traveled to a rescue shelter for slaves in the town of Atebubu and to Lake Volta, where many child slaves are working, said Peggy Callahan, the organization's co-founder and executive producer.
Callahan says she met Mraz through a mutual friend and she suggested he go to Ghana with her.
"The movement to end slavery really needs more voices, but they really need to be authentic voices, people who really do care about an issue," she said. "And Jason's one of those people, and he's willing to take the time to find out."
Mraz is the first celebrity to participate on the ground with the organization.
The pop singer is also busy working on the follow-up to his platinum-selling CD, 2008's "We Sing. We Dance. We Steal Things."
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