During South Africa’s apartheid period, Mosher was a frequent visitor to Johannesburg and Soweto. He organized the first-ever festival of South African drama ("Woza Afrika!") at Lincoln Center, showcasing theatrical productions and funneling tens of thousands of dollars to Township arts groups and individual artists. In 2015, he traveled with a young company to perform Sophocles' "Antigone" in schools, community centers, and a juvenile prison in Nairobi and the Cape Town and Johannesburg townships. In 2017, he directed the American premiere of Ferdinand Von Schirach's "Terror" for Miami New Drama at the Colony Theatre.