An agglomeration, or urban agglomeration, is an administrative subdivision of Quebec at the local level that may group together a number of municipalities which were abolished as independent entities on 1 January 2002 but reconstituted on 1 January 2006.
Urban agglomerations have certain powers that would ordinarily be exercised by individual municipalities.
The province of Quebec undertook several municipal amalgamations in the early to mid-2000s. This proved to be controversial in several municipalities, and in the aftermath, several municipalities voted in a 2004 referendum to reverse their amalgamation. However the supralocal urban agglomeration level of government was retained over each formerly merged region.
The Act respecting the exercise of certain municipal powers in certain urban agglomerations defines the expression urban agglomeration as follows.
- An urban agglomeration corresponds to the territory, as it exists on 17 December 2004, of Ville de Montréal, Ville de Québec, Ville de Longueuil, Ville de Mont-Laurier, Ville de La Tuque, Municipalité des Îles-de-la-Madeleine, Ville de Sainte-Agathe-des-Monts, Ville de Mont-Tremblant, Ville de Cookshire-Eaton, Ville de Rivière-Rouge or Ville de Sainte-Marguerite–Estérel.
One municipality in each agglomeration is known as the central municipality and has special status under the Act. The others are called related municipalities.
The Act defines the powers exercised by the agglomeration and those exercised by the reconstituted municipalities, known as agglomeration powers (compétences d'agglomération) and local powers (compétences de proximité).
Agglomeration powers are exercised by agglomeration councils (conseils d'agglomération).
These are defined by statute. Many governmental functions are performed by the central city in each agglomeration; for example, the Montreal city police (SPVM) have jurisdiction in the neighboring communities.
A list of these can be found on the website  of the Ministère des Affaires municipales et régionales.
List of constituent municipalities
In each list, the legally designated central municipality appears first.
- Ville de Montréal
- Ville de Baie-D'Urfé
- Ville de Beaconsfield
- Ville de Côte Saint-Luc
- Ville de Dollard-Des-Ormeaux
- Ville de Dorval
- Ville de Hampstead
- Ville de Kirkland
- Ville de L'Île-Dorval
- Ville de Montréal-Est
- Ville de Montréal-Ouest
- Ville de Mont-Royal
- Ville de Pointe-Claire
- Ville de Sainte-Anne-de-Bellevue
- Village de Senneville
- Ville de Westmount
- Ville de Longueuil
- Ville de Boucherville
- Ville de Brossard
- Ville de Saint-Bruno-de-Montarville
- Ville de Saint-Lambert
- Local government in Quebec
- Municipal reorganization in Quebec
- Administrative subdivisions of Quebec
- Metropolitan Community (Quebec)