Devens is a regional enterprise zone and census-designated place in the towns of Ayer and Shirley (in Middlesex County) and Harvard (in Worcester County) in the U.S. state of Massachusetts. It is the successor to Fort Devens, a military post that operated from 1917 to 1996. The population was 1,840 at the 2010 census.

The area itself is named after jurist and Civil War general Charles Devens. In 2011, the CDP tried to secede from Ayer, Shirley, and Harvard and become the 352nd town in the Commonwealth of Massachusetts but failed the vote. Some residents are still looking to secede to become a town.

The area operated as Fort Devens from 1917 to 1996. The Fort’s sitting was due primarily to its location at a major hub of the rail network in New England. Since 1917, a formerly sleepy area was developed into a fort that was later redeveloped into the industrial area of Devens. Federal Medical Center, Devens was established as a federal prison on the grounds of the former base.

The U.S. Army post which resided at Fort Devens was officially closed in 1996 after 79 years of service. The process for land distribution for all parcels on the former Fort Devens allowed the Federal Bureau of Prisons, Shriver Job Corps, Massachusetts National Guard, Massachusetts Veterans and MassDevelopment to acquire the land. The bulk of the land was purchased by MassDevelopment for $17 million. MassDevelopment is a quasi-public development authority that has been given the task of turning Devens into a residential and business community. Since the closing of the military base, many of the existing buildings have been renovated or reconstructed; housing developments now exist, along with a growing business park, a new hotel, restaurants, two disc golf courses and a golf course. Veterans of the Army Security Agency have also expressed interest in building a museum there, as Fort Devens was their principal training facility for more than two decades.^{[citation needed]}

A comprehensive disposition process has been ongoing since 2003, charged with determining the future political governance of Devens. During 2005-06 it was determined that the governance scenario best suited for the regional stakeholders was to create a new independent town. On October 24, 2006, a vote to confirm the disposition recommendation for future governance was voted down by 2 of the 6 stakeholders, the adjoining towns of Harvard and Ayer (residents of Shirley, the Devens residents, MassDevelopment and the Devens Enterprise Commission supported the resolution). On November 7, 2006 during the State elections the second opportunity to vote on Devens disposition had only Harvard voting against the scenario with the towns of Ayer and Shirley supporting Devens as a town. Devens’s disposition will now be determined by another disposition process or by the state legislature. Residents of Devens vote in either Harvard or Ayer but still have no elected representatives that have municipal authority in Devens. MassDevelopment maintains the utilities (such as gas, electricity and water) and contracts out public safety services such as firefighting and police.

Devens is home to, among other enterprises, New England Studios, a film studio opened in 2014 and Commonwealth Fusion Systems, an MIT spinoff which raised $1.8 billion in December, 2021 to build a tokamak fusion device.