Deux-Montagnes (French pronunciation: [dø mɔ̃taɲ]) is a regional county municipality in the Laurentides region of Quebec, Canada. It is located immediately north of Laval on the north shore of the Rivière des Mille-Îles and on the north shore of the Lake of Two Mountains. Its seat and largest city is Saint-Eustache.

The municipality has a land area of 242.88 km and its population was 102,052 residents as of the 2021 Census.

There are 7 subdivisions and one native reserve within the RCM:

Historical Census Data - Deux-Montagnes Regional County Municipality, Quebec

Year Pop. ±% 1991 71,218 —     1996 78,960 +10.9% 2001 81,417 +3.1% 2006 87,249 +7.2%	Year Pop. ±% 2006A 87,264 +0.0% 2011 95,670 +9.6% 2016 98,203 +2.6% 2021 102,052 +3.9%
(A) adjustment due to boundary change.

Canada Census Mother Tongue - Deux-Montagnes Regional County Municipality, Quebec
Census		Total		French				English				French & English				Other
Year		Responses		Count	Trend	Pop %		Count	Trend	Pop %		Count	Trend	Pop %		Count	Trend	Pop %
2021		101,660		84,690	0.5%	83.3%		5,620	1.8%	5.53%		1,685	50.58%	1.66%		8.135	30.68%	8%
2016		97,960		85,125	1.3%	86.9%		5,520	6.5%	5.6%		1,090	20.4%	1.1%		6,225	63.4%	6.4%
2011		94,620		84,000	8.4%	88.78%		5,905	3.3%	6.24%		905	28.4%	0.96%		3,810	42.7%	4.03%
2006		86,570		77,480	6.3%	89.50%		5,715	1.9%	6.60%		705	9.0%	0.81%		2,670	72.8%	3.08%
2001		80,810		72,880	4.2%	90.19%		5,610	8.9%	6.94%		775	2.6%	0.96%		1,545	8.8%	1.91%
1996		78,280		69,945	n/a	89.35%		6,160	n/a	7.87%		755	n/a	0.96%		1,420	n/a	1.81%

Highways and numbered routes that run through the municipality, including external routes that start or finish at the county border:

• List of regional county municipalities and equivalent territories in Quebec
• CIT Laurentides
• Deux-Montagnes (AMT)