Bancroft accepted an offer from the Trustees of Phillips Academy while in Italy and was officially named 8th Principal on May 17, 1873. He began his tenure later that year, arriving in Andover on July 31, 1873, living in Double Brick House. He came at a time of decline for the school. Funds were low, student enrollment was decreasing, and the school's reputation was falling. As Principal, he took advantage of the school's centennial celebration in 1878 to launch a campaign, reaching out to alumni, decedents of alumni and founders of the school, and others. Over the next two decades he brought about the creation of new buildings, increased the size of the faculty from eight to 22 and the student body from 237 to over 400, and added significantly to the endowment, all of which added to the quality of education. Bancroft was a trustee of Dartmouth College, the Andover Theological Seminary, the State Hospital at Tewksbury, and the State Farm at Bridgewater.
