The Ketti Frings play "The Cool World" only lasted for two shows, but Calvin was soon cast in a controversial stage role in the play "A Taste of Honey", a play about a soldier who has fallen in love with a white woman. As more roles became scarce for him as a black actor, he moved to Europe for more work.
He first moved to Italy, where he owned a theatre company and a restaurant. He later moved to West Germany, then England where his film credits began to build up. His first major role would finally come in the 1967 film Joanna, a film about interracial romance.
With a lot of experience and credits, Calvin returned to the United States and soon became a sought after actor there. His first major role in the US was as the lead character in 1970's Halls of Anger. Then, he would go on to play Reverend Deke O'Malley in Cotton Comes to Harlem, a role that would mark the beginning of success in American Film, particularly Black Cinema.