The regional chambers of England were a group of indirectly elected regional bodies that were created by the provisions of the Regional Development Agencies Act 1998. There were eight regional chambers, one for each of the regions of England except Greater London, which had opted for an elected mayor and assembly in 1998. All eight regional chambers had adopted the title "regional assembly" or "assembly" as part of their name, though this was not an official status in law. The chambers were abolished over a two-year period between 31 March 2008 and 31 March 2010 and some of their functions were assumed by newly established local authority leaders' boards.

The additional-member system (AMS) is a mixed electoral system under which most representatives are elected in single-member districts (SMDs), and the other "additional members" are elected to make the seat distribution in the chamber more proportional to the way votes are cast for party lists. It is distinct from parallel voting in that the "additional member" seats are awarded to parties taking into account seats won in SMDs, which is not done under parallel voting.