A quiet yet dynamic place to study and to do research, Flagler Memorial Library is named in honor of Harry Harkness Flagler, first president of the Board of Trustees (1932 – 1952) and an early and important benefactor of the school.
Flagler Memorial Library has a collection of over 22,000 holdings among which are several special collections, including 1,400 reference works, approximately 80 magazine subscriptions and more than 600 videos and DVDs. In addition, the Holbrook Art Center houses the David Holbrook Art Library, a special reference collection of works on the arts. Millbrook students have access, as well, to materials in a variety of digital formats, from databases to collections of primary sources to electronic books. To further augment the collection, the library is able to practice inter-library loan, regionally and nationally, with the Dutchess County BOCES, the South Eastern New York Library Resources Council, the Mid-Hudson Library System, and the New York State Library. These associations provide the Millbrook School community with the opportunity to borrow from school, college, and university libraries as well as other educational and public institutions.