North Andover is a town in Essex County, Massachusetts, United States. At the 2020 census, the population was 30,915.

Native Americans inhabited what is now northeastern Massachusetts for thousands of years prior to European colonization of the Americas. At the time of European arrival, Massachusett and Naumkeag people inhabited the area south of the Merrimack River and Pennacooks inhabited the area to the north. The Massachusett referred to the area that would later become North Andover as Cochichawick.

The lands south of the Merrimack River around Lake Cochichewick and the Shawsheen River were set aside by the Massachusetts General Court in 1634 for the purpose of creating an inland plantation. The Cochichewick Plantation, as it was called, was purchased on May 6, 1646, when Reverend John Woodbridge, who had settled the land for the English, paid Massachusett sachem Cutshamekin six pounds and a coat for the lands. The plantation was then incorporated as Andover, most likely in honor of the hometown of many early residents, Andover, Hampshire, England. The town was centered in what is now North Andover, but the spread of settlement south and west of the old town center created much conflict in the early years about the location of the parish church. In 1709, the matter was brought to the General Court, which set aside two parish churches, north and south. The parishes grew apart as the years went on and on April 7, 1855, the North parish separated from the south and was incorporated as North Andover.

There are several first-period (pre-1720) houses still standing in town. The oldest house is the Bridges House, relocated from Marbleridge Road to Court Street in 2001; the original portion of this house dates to about 1690. Other first-period houses include the Stevens House on Great Pond Road; the Faulkner House on Appleton Street; the Abiel Stevens House on Salem Street; the Parson Barnard House, which is a museum; a house on Andover Street near the intersection with Chickering Road; and the Carlton-Frie-Tucker House at 140 Mill Road. No house in North Andover has been scientifically dated by dendrochronology, so dates are based solely on stylistic elements, original deeds, and tradition.

The North Parish Church on the North Andover Green is a historic church building built in 1836. It was the 5th meetinghouse of the Puritan church congregation founded in 1645 in North Andover. In about 1836, the congregation became a Unitarian church and commissioned this Gothic building.

North Andover's development was varied, with much of the land along the Shawsheen and Merrimack being concerned with industry, and the lands southwest being more agricultural. Several mills were located in the town, as well as the Western Electric Company, AT&T's manufacturing division, which supplied telephone machinery for many years before AT&T split it up into the new company, Lucent Technologies. Today, North Andover is considered a bedroom community of the Greater Boston area.

In January 2018, voters turned down a proposal for a cannabis-growing and research facility in the former Lucent Technologies building, along the Merrimack River. The town meeting vote was 1,430 against having recreational marijuana facilities and 1,155 voted in favor. The growing and research facility was expected to bring the town $100 million over a 20-year period.

According to the United States Census Bureau, the town has a total area of 27.8 square miles (71.9 km²), of which 26.3 square miles (68.1 km²) is land and 1.4 square miles (3.7 km²), or 5.18%, is water. The town lies to the south of the Merrimack River, which makes up part of its northwestern boundary, along with the Shawsheen River. The northeastern quadrant of town is dominated by Lake Cochichewick, which is also bordered by the Osgood Hill Reservation, Weir Hill Reservation, and the Reas Pond Conservation Area. The town is also home to portions of Harold Parker State Forest, Boxford State Forest, and the Charles W. Ward Reservation. There are many brooks, streams, and ponds dotting the town.