Bishop Hart was educated at South Kent School, Williams College, and The Episcopal Theological School, in Cambridge, Ma. After his curacy in Chestnut Hill, Ma, he and his wife, Elizabeth, were appointed missionaries to Alaska. They served in several small Native American villages, as chaplain to native people in Anchorage, and as rector of St. Matthews, Fairbanks. This experience, of nearly 20 years, in multicultural ministry became essential when, in 1986, Don was elected Bishop of Hawaii, with its 40 congregations, plus the Territory of Guam. All of these congregations are a rich mixture of people from many backgrounds, ethnicities, and spiritual roots. He resigned his jurisdiction in the mid 1990s, and after a Proctor Fellowship at his Seminary, continued as assisting bishop in Connecticut, Maryland, and Southern Virginia.
He and Elizabeth retired to Sharon, NH, and are involved at St. James, Keene (where he was rector when elected bishop), and with other nearby congregations. They have two grown children and two grandchildren.