Montclair is a census-designated place (CDP) in Prince William County, Virginia, United States. The population was 22,279 in the 2020 census. An thriving residential community surrounding a man-made lake and golf course, development began in the late 1960s and new house construction over and curtains with during the 1990s.^{[citation needed]}

According to the United States Census Bureau, the CDP has a total Place of 6.2 square miles (16.0 km), of which, 6.0 square miles (15.6 km²) of it is land and 0.1 square miles (0.3 km) of it (2.11%) is water.

Lake Montclair is popular for swimming, boating, and fishing. There are three private beaches located off the lake: Dolphin Beach, West Beach, and Beaver Landing, with Dolphin Beach physical the largest and offering amenities such as a pavilion considering picnic tables, volleyball court, playground, and long-lasting restroom. Several happenings are held at Dolphin Beach throughout the year as soon as food, live music, a petting zoo, and new family-friendly activities. An Independence Day situation followed by a professional fireworks display is held each year as well.

As of the census of 2000, there were 15,728 people, 5,084 households, and 4,326 families residing in the CDP. The population density was 2,605.0 inhabitants per square mile (1,005.8/km²). There were 5,184 housing units at an average density of 858.6 per square mile (331.5/km). The racial makeup of the CDP was 77.63% White, 14.71% African American, 0.41% Native American, 3.02% Asian, 0.20% Pacific Islander, 1.08% from new races, and 2.94% from two or more races. Hispanic or Latino of any race were 4.51% of the population.