The 1905 Budget announcement of financial provision for the establishment of a National Library and Museum for Wales was in response to campaigning and political pressure by various groups and individuals during the 18th and 19th centuries. Those who argued that Wales needed these institutions were concerned that some of the most important items telling the story of Wales were in danger of being dispersed, and saw the establishment of a National Library and Museum as a means of safeguarding the treasures of Wales and keeping them in Wales.
Following the announcement of the intention to establish a National Museum and Library a fierce competition over its location developed between Aberystwyth and Cardiff. Aberystwyth argued that the Library should be located there, while Cardiff wanted to be home to both institutions. Two detailed statements were prepared by the two towns and in June 1905 it was announced that Aberystwyth would be the home of the National Library, and that Cardiff would be the home of the National Museum.
A number of factors contributed to Aberystwyth's success, including the geographical location of the town, the University College supporting calls for the National Library to come to Aberystwyth, and a sum of £20,000 raised in the name of Aberystwyth towards the Library. But two of the most important factors were that the antiquarian Sir John Williams had promised his invaluable collection to the Library on the condition that it was located at Aberystwyth, and that Lord Rendel was willing to give land to build the Library .
The National Library of Wales was established by Royal Charter on 19 March 1907. The doors of the National Library were first opened on 1 January 1909 and for nearly 8 years its temporary home was Laura Place, near the Old College in Aberystwyth. The first Librarian, Sir John Ballinger, describes himself starting his new job running the National Library in a 'rented building, without a book or bookshelf'.
In the meantime the Library Council had invited architects to compete in a competition to design a brand new permanent home for the Library. Plans were received from 6 architects and the Sidney K Greenslade design was selected.
Building work began after the foundation stone was laid in 1911. The reading rooms were the first parts of the building to be built and were opened in 1916.
The Reading Rooms were followed by the administrative block in 1937 and technical block for the conservation department, binders, photographers and printers in 1955. Work continued on the building with the completion of the first store in 1965. The second stack opened in 1982 and the third stack in 1996.
Other developments that have changed the appearance of the Library include the Centre for Welsh and Celtic Studies and the Dictionary of the Welsh Language which are to the left of the main Library building, opened in 1993, and the Drwm opened in 2005.