Frank Mosher Library was named after Gouverneur Frank Mosher, the second missionary bishop in the Philippines during the 1930's to 1940's. It was built together with the theological seminary as an aid to the information needs of the students.
In 1960's, the library was a recipient of grants from Bernard C. Nelson Fund, the Board of Founders of the Nanking Theological Seminary, and the Theological Education Fund. From time to time, individual gifts and collection of books were donated. Among these are gifts from Bishop Norman Spencer Binsted.
During the 1990's, the Mosher Library was one of the finest theological libraries in Southeast Asia and has about 30,000 volumes and 250 periodicals. It was the official repository of Master of Theology theses of the South East Asia Graduate School of Theology( SEAGST) in the Philippine arena and of the archives of the Iglesia Filipina Independiente (IFI).
Some of the special collections built were Filipiniana and Igorot Studies. It has a rich collection of primary materials on the urban-industrial mission in the Philippines.
Frank Mosher Library had acquired more than 40,000 volumes over the years. Its active collection is more than 22,000 volumes. Until now, the library continues to develop an avenue of quality theological information as well as quality services.