Shirley is a town in Middlesex County, Massachusetts, United States. It is approximately thirty miles west-northwest of Boston. The population was 7,431 at the 2020 census. The town has a well-preserved historic New England town center.

It is home to the Massachusetts Correctional Institution – Shirley, a medium-security state prison. (The neighboring maximum-security Souza-Baranowski Correctional Center lies just outside the town limits in the town of Lancaster.) The remains of a Shaker village have been preserved within the grounds of the prison.

The inhabitants at the time of European encounter were Nipmuc (or Pennacook) Indians, who called the area Catacunemaug. Once part of “The Plantation of Groton,” Shirley was first settled by English pioneers about 1720.

In 1753 it separated from Groton and was incorporated, named in honor of William Shirley, governor of Massachusetts (1741–1757). The town established a paper mill around 1790, and the first of seven cotton mills in 1812. Other local products included iron, nails, textiles, rope, belts, suspenders, and athletic equipment. Two of the large 19th-century mill buildings have been subdivided and adapted for use by 21st-century businesses.

A utopian religious community, Shirley Shaker Village, was established in Shirley in 1793. The Shakers advocated pacifism, common property, celibacy, and communal living. They are renowned for their plain architecture and furniture. The Shaker movement peaked in the 1840s, but gradually dwindled, perhaps because of greater employment opportunities offered by the Industrial Revolution, or because succeeding generations grew less tolerant of the Shaker church’s insistence on self-abnegation. Shirley Shaker Village closed in 1908.

A medium-security state prison was built on land surrounding the remains of the Shaker village in Shirley, and continues to operate. The town also operates a Senior Center located at 9 Parker Road, which previously was a preschool/kindergarten.