The Peace Palace Library possesses a unique and important collection on several peace movements from the period 1899-1940, brought together by J.C. ter Meulen, Head Librarian 1924-1952. The Peace Movement collection consists of books, brochures, pamphlets, conference reports, newspaper clippings, letters and photographs from pacifist organizations and individuals connected with these organizations. These groups and individuals all strived for world peace in the period 1900-1940. Most of the materials are in Dutch, but there are also books and documents in English, German, French or other languages.
All items in the Peace Movement collection were added to an inventory list, published in J. Haasbeek (ed.), Vredescollectie: Collection of Dossiers concerning the Peace Movement, 1993.
Not only were all documents described, but all items in the 55 folders were put on microfilm and photographed in 2004-2005 under the Metamorfoze project of the Koninklijke Bibliotheek, National Library of the Netherlands. Each item was also scanned and is now available in separate pdf files, so all texts in this collection are available online.