| 26 August 1971 | The OCLC Online Union Catalog, now called WorldCat, goes online |
| 1975 | Library and Archives Canada begins adding records for serial publications to WorldCat via the CONSER program |
| 1978 | Koninklijke Bibliotheek (The National Library of the Netherlands) obtains 400,000 records from WorldCat |
| 1985 | The British Library begins adding UKMARC records to WorldCat, which since has resulted in 9.2 million records |
| 1987 | The National Library of Scotland begins adding records to WorldCat |
| 1987 | The National Library of Wales begins contributing records to WorldCat |
| 1987 | The National Central Library, Taiwan, begins adding holdings to WorldCat |
| 1991 | Six staff members from the National Library of China spend a year at OCLC creating a computerized catalog of Chinese books for WorldCat |
| 1991 | The National Library of Turkey becomes an OCLC member and begins using the OCLC online system for cataloging |
| 1992 | The National Library of Australia begins contributing records to WorldCat |
| 1992 | The National and University Library of Iceland begins adding holdings to WorldCat |
| 1995 | The National Library of the Czech Republic begins contributing records to WorldCat |
| 1997 | The National Library of New Zealand begins contributing records to WorldCat |
| 1998 | The National Library of Ireland begins adding records to WorldCat |
| 1999 | The National Diet Library of Japan begins adding records and holdings for Western-language materials to WorldCat |
| 1999 | The National Library of Lithuania begins contributing records to WorldCat |
| 1999 | The National Library of South Africa begins adding records to WorldCat |
| 2000 | Library and Archives Canada begins loading records directly into WorldCat |
| 2002 | 1.4 million holdings from the Singapore National Union Catalog are added to WorldCat |
| 2003 | Deutsche Nationalbibliothek (The German National Library), the Library of Congress and OCLC agree to develop a Virtual International Authority File |
| 2003 | The Chilean Directorate of Libraries, Archives, and Museums (DIBAM) of the National Library and the 368 public libraries it manages in Chile become governing members and begin contributing their current cataloging to WorldCat |
| 2004 | The National Library of Australia selects the OCLC Central Bibliographic System (CBS) to support the Australian National Bibliographic Database and Kinetica system, the Internet-based service for Australian libraries and their users |
| 2004 | 410,000 holdings from the National Library of Chile—including 230,000 original records—are added to WorldCat |
| 2004 | Bibliothèque nationale de France begins contributing holdings to WorldCat |
| 2005 | The National Library of Jamaica begins using CONTENTdm to digitize Jamaican heritage materials |
| 2005 | The National Library of Finland adds more than 600,000 new records from the Finnish national bibliography into WorldCat |
| 2005 | The Iraqi National Library and Archive begins adding records to WorldCat |
| 2006 | Deutsche Nationalbibliothek (The German National Library) adds 4 million new records to WorldCat |
| 2006 | The Dutch Union Catalog (more than 9 million records) is added to WorldCat, resulting in 4 million new records and over 20 million holdings |
| 2007 | The National Library of Mexico agrees to add its catalog to WorldCat |
| 2007 | The Swiss National Library loads 1.3 million records to WorldCat |
| 2007 | The National Library of New Zealand loads 4 million records and the holdings of 275 New Zealand libraries to WorldCat |
| 2007 | The National Library of Australia loads 17 million records and the holdings of more than 800 Australian libraries into WorldCat |
| 2007 | Kungl. Bibliotheket (the National Library of Sweden) loads 2 million records into WorldCat |
| 2007 | The National Central Library, Taiwan, adds all of its records and holdings to WorldCat |
| 2008 | The National Library of China agrees to load 1.5 million records into WorldCat |
| 2008 | The National Library Service, Barbados loads holdings into WorldCat |
| 2008 | The National Library of Israel loads more than 788,000 records into WorldCat |
| 2008 | The National Library of Spain agrees to load 3 million records into WorldCat |
| 2008 | As a result of an agreement with the Danish Agency for Libraries and Media, the records and holdings of the Royal Library of Denmark, along with the other participants of the Danish Bibliographic Centre, will be added to WorldCat |
| 2009 | The The National and University Library of Slovenia begins adding records and holdings to WorldCat along with other Slovenian libraries that are part of the IZUM consortium |
| 2010 | The National Library of Serbia agrees to add its records and holdings to WorldCat along with those of other Serbian libraries |
| 2010 | The National Diet Library of Japan agrees to add the Japanese National Bibliography to WorldCat |
| 2012 | The National Library of Norway begins adding records and holdings to WorldCat along with other libraries that useBIBSYS services |
