Joseph always wanted to be a teacher, and, though there were many job options in his country, never applied for anything other than teaching. After earning a Ph.D. at the University of Wisconsin and before coming to St. Olaf in 1990 to teach post-colonial and third-world literature, he taught in the Literature Department of the University of Dar es Salaam, Tanzania. Over the years, he has taught courses such as Swahili Literature, Theory of Literature, African Literature, Sociology of Literature, Post-Colonial and Third World Literature, The Epic, and African-American Literature.
Joseph likes western classical music, traditional folk music of different countries, reggae, rap, and "any great dance music, from Michael Jackson and Madonna to Zairian tunes." He lives in Northfield with his wife Heribertha, and they have three daughters.