Mark joined Groton School after working in university, community college, and independent school libraries. He studied librarianship at McGill University in Montreal. Working with archival and special collections drew him to library work, but it was the opportunity to help students gain mastery in information literacy that drew him to academic and school libraries. He originally trained as a historian at Yale and Boston College, where he pursued interests in the history of medicine and in Christianity in early modern Europe. He spent a year in Venice doing dissertation research in their state archives, reading sixteenth-century manuscripts and some of the earliest printed books.