This collection primarily documents Gerald H. Anderson's work as missionary educator in the Philippines, author, editor, and participant in many ecumenical mission conferences and groups. While Anderson was Associate Director and then Executive Director of the Overseas Ministries Study Center from 1974-2000, this collection does not document his work with OMSC except through some Director's reports and some correspondence in the 2019 Appendix. The collection was substantially augmented and re-ordered in 2013 as records from throughout Anderson's career were added to the existing collection that primarily documented his work on the Biographical Dictionary of Christian Missions, a work which includes extensive and comprehensive coverage of Christian missions with 2,400 original signed biographies by 350 authors from 45 countries.
The 2019 Appendix contains material similar to what is available elsewhere in the collection. It contains a broader range of General Correspondence than what is available in Series I of the original collection. Notable correspondents include Paul Clifford, Willi Henkel, W. Richey Hogg, Jan Jongeneel, Sebastian Karotemprel, Harold Metzner, Dana Robert, and Andrew Walls.