Carnegie libraries were the inspiration of the Scottish-American steel magnate Andrew Carnegie. Born in Scotland in 1835, Carnegie emigrated to the United States of America in 1848 and amassed a huge fortune through his creation and direction of the Carnegie Steel Company. Selling out to US Steel in 1901, Carnegie set about dispersing some 90% of his personal fortune, estimated at $480m, following the philanthropic doctrine he had developed and publicised in his essay, The Gospel of Wealth. As part of this endeavour, between 1883 and 1929, Carnegie's foundation deployed some $40m to fund the construction of some 2,500 libraries worldwide.
Some 35 such libraries were established in Wales. The provision of libraries focussed heavily on the industrialised, urban areas, such as the South Wales Valleys, and libraries in rural areas are rare. Grants were reliant on matched funding and local authorities were obliged to demonstrate that they could cover the costs of stocking the libraries, and ensuring their ongoing staffing and maintenance. Carnegie Foundation grants were generally in the range of ã2,000-ã8,000, though they could be lower, sometimes in the hundreds of pounds if refurbishment of an existing building was intended, or higher. Grants were both refused and declined when offered; in the former instance when local councillors were unable or unwilling to match the foundation's funding; in the latter case when they objected to Carnegie as benefactor, "a man perceived to have gained so much wealth from the subjugation of working people for his own profit".
The, "often innovative", designs of the libraries varied greatly; from simple single-storey structures, to buildings of greater elaboration in a variety of styles, including Gothic Revival, neoclassical and Baroque Revival. The peak years for construction were 1903-1911, with far fewer buildings put up before this date, and a major slow-down from World War I until the ending of the programme in the 1930s.
Approximately two thirds of the libraries are listed buildings but the aim of the Carnegie Foundation to ensure economy and functionality rarely attracted any but local, often municipal, architects to compete with designs. Of the twenty-one which are listed, twenty are at the lowest grade, Grade II, while only one, Cathays Library achieves the middle grade, Grade II*. Just under half of the libraries continue as local authority-operated public lending libraries, the purpose for which they were built. Of the remainder: some remain under public control, but have been repurposed; some have been sold and passed out of public control; and two have been demolished.