The National Democratic League was a cross-party political organisation in the United Kingdom, which aimed to unite Liberal Party and former Independent Labour Party (ILP) members in a campaign for basic democratic reforms.
The League was founded in October 1900 on the initiative of William Thompson, editor of Reynold's News. Concerned by the Conservative Party majority in the 1900 UK general election and the establishment of the Labour Representation Committee (LRC), he called the "Democratic Convention", aiming to bring together liberals and socialists on a basic democratic programme, inspired by Chartism. He was succeeded by Victor Fisher. Thompson served as the President, while David Lloyd George, Robert Smillie, W. C. Steadman and Richard Bell were among its Vice-Presidents.
Although initial interest soon faded, Mann's work led to a short revival in its fortunes in 1902. It appears to have dissolved some time after 1911.