The fundamental organizations for constitutional change in the British nations were local, town and city based. These could be quite large: for example, in 1793 the Leeds Constitutional Society claimed 2000 members, while the Sheffield Constitutional Society claimed 'several thousand'. A town could support several such organizations. These local societies began to combine first within towns (the Norwich United Political Societies claimed 30 to 40 separate member societies within the city itself) and then nationally, adhering to one or more of the national organizations. The most important of these were:
- The Society for Constitutional Information (or simply the Constitutional Society)
- The oldest of the national organizations, active from the 1770s, it had branches in most major towns in England, especially in the north: Derby, Stockport, Manchester, Sheffield, Nottingham, and others. For examples, see some of the entries in the Events section.
- The Revolution Society
- Founded in 1788 on the centenary of the 1688 Glorious Revolution, and with some branches across England.
- The Friends of the People
- Numerically small in England, but with a parliamentary faction led by Charles Grey. In Scotland, the same organization dominated nationally, and had a similar central role to that of the Society for Constitutional Information in England.
- The United Irishmen
- Founded in Belfast and soon expanded to cover Dublin and the rest of Ireland, this was the most determined of the societies and the only one to lead an insurrection which was a serious threat to the British Government. It inspired the creation of the short-lived United Scotsmen and the shadowy United Britons.
- The London Corresponding Society
- Originally created as a single organization for London, it rapidly expanded to have multiple divisions across the capital, and to supplement or replace the Society for Constitutional Information as a co-ordinating organization for the whole of England.
After the political defeat of these organizations, some activists were involved in new and more radical movements.
- The Spencean Philanthropists
- A group formed around Thomas Spence and led after his death until its prohibition by Thomas Evans.