The 2000–2006 municipal reorganization in Quebec resulted in large-scale amalgamation (merging) of smaller municipalities in Quebec into larger cities. It was undertaken by one administration, and modified and partially undone by its successor.
The first phase involved a large number of amalgamations from late 2000 until 2003, undertaken by the Parti Québécois government of Québec, headed by Premier Lucien Bouchard and his successor Bernard Landry. The most significant amalgamations, involving the largest cities in Quebec, mostly occurred on January 1, 2002. Some of the mergers were unpopular, and this became an issue in the April 14, 2003 Quebec election, in which the victorious Quebec Liberal Party led by Jean Charest campaigned on a promise to allow residents the right to choose to de-merge and reconstitute their former municipalities.
The new administration held referendums in various municipalities in 2004 to fulfill its campaign promise; however, a number of conditions were imposed, including a minimum voter participation threshold, which meant that not all merged municipalities held referendums and even fewer actually de-merged. The de-mergers that succeeded became effective on January 1, 2006. However, a new type of municipal structure, an urban agglomeration was created, which continued to tie the newly independent de-merged municipalities to their former amalgamation partners for the provision of certain municipal services.
The 2000–2003 municipal mergers were imposed on municipalities by the Québec government, however a number of voluntary amalgamations (arranged by municipalities themselves) had taken place in the 1990s (see Municipal history of Quebec); these earlier amalgamations were not subject to de-merger referendums. Municipal amalgamations had been encouraged by the Quebec government on the grounds they would result in greater efficiencies and cost savings; critics disputed this. The government also cited the precedent of the 1998 amalgamation of Toronto and the 2001 amalgamation of Ottawa.