National (and European) associations of local and regional authorities play a role in promoting local democracy which is vital to the work of the Congress of the Council of Europe.
They relay information about Congress activities across to their countries, particularly by lobbying their governments. They also, in some cases, play a part in the procedure whereby their country's national delegation to the Congress is designated.

As well as serving as a peaceful counterweight, they contribute know-how, experience and expertise which enhances the value of the Congress’ work.

National associations regularly rely on the standards set by the Congress in their discussions with national governments. The European Charter of Local Self-Government, which is legally enforceable against the states which have ratified it, is a particular weapon for use in their discussions with their governments on local democracy issues.

National associations play an active part in implementation of the provisions of the European Charter of Local Self-Government, complaining about abuses and possible violations and thus acting as an "early warning system", showing where monitoring and legal intervention by the Congress are needed.

The "Assises" of the national associations of local and regional authorities" were first held by the Congress in 2006. At this annual meeting common priorities emerge, and further discussions take place between the associations and the Congress of the Council of Europe.