Brentwood is a town in Rockingham County, New Hampshire, United States. At the 2020 census, its population was 4,490.^[2] Brentwood has been the county seat of Rockingham County^[3] since 1997.

An Abenaki tribe called the Pennacook farmed, fished and hunted in what is now Brentwood. Two main foot trails ran through the town, one along the Exeter River, where arrowheads and other stone and wooden artifacts have been found. At Pickpocket Dam, this pathway joined with the Pentucket Trail leading south to Pentucket (now Haverhill, Massachusetts) and north further into Pennacook territory.

The first non-native settlers came in 1652 to start a sawmill powered by a waterfall on the Exeter River.^[4]

Brentwood is a nearly square quadrangle, except that the town line follows the Exeter River in the southeastern corner. Brentwood has a total area of 17.0 square miles (44.0 km²), of which 16.8 square miles (43.6 km²) are land and 0.2 square miles (0.4 km²) are water, comprising 0.93% of the town.^[1] The highest point in Brentwood is Great Hill, at 275 feet (84 m) above sea level, whose summit is in the southeastern corner of the town.

The town is drained by the Exeter River and its tributary Dudley Brook. The Piscassic River, a tributary of the Lamprey River, crosses the northwestern corner of the town. Brentwood lies fully within the Piscataqua River (Coastal) watershed.^[14]

Brentwood's executive is a five-person board of selectmen, serving staggered three-year terms and meeting weekly (biweekly in spring and summer).^[15] Brentwood's legislature is a town meeting, held in March, at which every registered voter can vote on the annual town budget and amendments to it. The Swasey Elementary School has a separate town meeting. Classes above Grade 6 travel to regional schools in School Administrative Unit (SAU) 16.^[16]

SAU 16 is governed by official ballot referendum (SB 2), in which there is a "deliberative" town meeting but the final vote is by secret ballot in all participating towns, at the same annual election at which voters elect town and school officials. Every town in SAU 16 votes on the representative(s) of it and of all other towns in SAU 16.

Citizen petitions have sought to change Brentwood's two town meetings to SB 2, but have always fallen short of the 60% vote required.

exits serving Brentwood

Exit 7	(Calef Road)
Exit 8	North Road to

Middle Road (Route 111A) runs east/west and bisects the town. Other east/west roads are North Road and South Road. Calef Road (Route 125) is the principal north/south road.

The expressway Route 101 approximately follows Brentwood's northern boundary. It provides access to Manchester and to the Seacoast. Route 101 crosses into northeast Brentwood, as does Route 27 (old 101) beyond it. Part of New England Dragway is in Brentwood.

Route 111A east to Exeter gains access to Route 7 of the COAST bus system,^[17] and to a train station served by the Amtrak Downeaster.^[18] At the park and ride lot off Calef Road just north of Brentwood, there is bus service to Boston, Massachusetts and its Logan Airport. Shuttle bus service can be arranged to Manchester Boston Regional Airport.^[19]

The original church, on Route 111A, is now known as the Pilgrim United Church of Christ, Brentwood-Kingston.^[20] In addition, Brentwood First Baptist Church has been at the same location since 1771.^[21] Grace Ministries holds religious services and a Christian grade school in a former industrial building on Calef Road.^[22] There is also a Kingdom Hall of Jehovah’s Witnesses, which has two congregations.^[23]

As of the census of 2010, there were 4,486 people, 1,319 households, and 1,087 families residing in the town. The population density was 267.0 inhabitants per square mile (103.1/km²). There were 1,350 housing units at an average density of 80.4 per square mile (31.0/km²). The racial makeup of the town was 96.3% White, 0.7% African American, 0.1% Native American, 1.0% Asian, 0.1% Pacific Islander, 0.5% some other race, and 1.3% from two or more races. Hispanic or Latino of any race were 1.5% of the population.^[25]

There were 1,319 households, out of which 46.2% had children under the age of 18 living with them, 71.6% were headed by married couples living together, 7.1% had a female householder with no husband present, and 17.6% were non-families. 14.0% of all households were made up of individuals, and 5.9% were someone living alone who was 65 years of age or older. The average household size was 3.02, and the average family size was 3.33.^[25]

In the town, the population was spread out, with 26.6% under the age of 18, 7.2% from 18 to 24, 24.0% from 25 to 44, 28.8% from 45 to 64, and 13.4% who were 65 years of age or older. The median age was 41.1 years. For every 100 females, there were 106.1 males. For every 100 females age 18 and over, there were 106.6 males.^[25]

For the period 2007–2011, the estimated median annual income for a household in the town was $110,250, and the median income for a family was $111,650. Male full-time workers had a median income of $69,565 versus $55,000 for females. The per capita income for the town was $37,385. About 1.0% of families and 2.2% of the population were below the poverty line, including 3.2% of those under age 18 and 0.4% of those age 65 or over.^[26]

• Ted King (born 1983), professional cyclist
• Joshua Smith (1760–1795), author, minister
• William Morrill Wadley (1813–1882), railroad superintendent