This is a list of law enforcement agencies in the Commonwealth of Massachusetts.

According to the US Bureau of Justice Statistics' 2018 Census of State and Local Law Enforcement Agencies (CSLLEA), the state had 374 law enforcement agencies employing 19,578 (sworn) personnel (27,489 personnel, total, including sworn and non-sworn positions), with an average of 284 sworn personnel per 100,000 residents (compared to the national average of 241 sworn personnel per 100,000 residents, with Massachusetts maintaining approximately 16% more sworn personnel per 100,000 residents than the national average).

Between the previous CSLLEA (in 2008) and the 2018 CSLLEA, Massachusetts saw an increase of 357 law enforcement agencies to 374 (an increase of 17 agencies or 4.6%). Sworn personnel would increase from 18,342 to 19,578 (an increase of 1,236 or 6.5%). Sworn personnel would increase from 280 per 100,000 state residents to 284 per 100,000 residents (an increase of 4 per 100,000 or 1.4%).2008 Census of State and Local Law Enforcement Agencies, by Brian A Reaves, US Department of Justice, Office of Justice Programs, Bureau of Justice Statistics, July 2011

As of 2022, Massachusetts ranked 26th out of 50 in violent crime rates, ranked ranked 5th-lowest (45th out of 50) in homicide rates, and was the ranked second-lowest (48th out of 50) in property crime rates as of 2019.

State agencies Alcoholic Beverages Control Commission Enforcement Division (certain investigators may be sworn as "special state police officers" (SSPOs)) Division of Police Standards, Massachusetts Peace Officer Standards and Training Commission (MPOST-C) Massachusetts Environmental Police Massachusetts State Police Massachusetts Parole Board Massachusetts Department of Correction Massachusetts Probation Service Trial Court Security Department

Alcoholic Beverages Control Commission Enforcement Division special investigators, Massachusetts Department of Correction officers, Massachusetts Parole Board officers, Massachusetts Probation Service officers, and Massachusetts Trial Court Security Department officers are not subject to the MPOST-C's regulations nor certification process. This restricts their ability to act as law enforcement officers in all but very specific circumstances.

County agencies

Barnstable County Sheriff's Office Berkshire County Sheriff's Office Bristol County Sheriff's Office Dukes County Sheriff's Office Essex County Sheriff's Office Franklin County Sheriff's Office Hampden County Sheriff's Office Hampshire County Sheriff's Office Middlesex County Sheriff's Office Nantucket County Sheriff's Office Norfolk County Sheriff's Office Plymouth County Sheriff's Office Suffolk County Sheriff's Department Worcester County Sheriff's Office

County sheriff's angencies are not automatically subject to the MPOST-C's regulations nor certification process. This restricts their ability to act as law enforcement officers in all but very specific circumstances. Sheriff's personnel that meet the MPOST-C standards and are certified, however, are considered "law enforcement officers" under Massachusetts law and are not subject to the same restrictions.

Municipal agencies

Abington Police Department Acton Police Department Acushnet Police Department Adams Police DepartmentAdams Police Officer charged with using false identity to fill prescription; 20 August 2014, Berkshire Eagle Agawam Police Department Alford Police Department Andover Police Department Amesbury Police Department Amherst Police Department Arlington Police Department Ashburnham Police Department Ashby Police Department Ashfield Police Department Ashland Police Department Aquinnah Police Department Athol Police Department Attleboro Police DepartmentOfficial web site accessed 23 October 2014 Auburn Police Department Avon Police Department Ayer Police Department Barnstable Police DepartmentOfficial web site accessed 23 October 2014 Barre Police Department Becket Police Department Bedford Police DepartmentOfficial web site accessed 23 October 2014 Belchertown Police Department Bellingham Police Department Belmont Police Department Berkley Police Department Berlin Police Department Bernardston Police Department Beverly Police Department Billerica Police Department Blackstone Police Department Bolton Police Department Boston Police DepartmentOfficial web site accessed 23 October 2014 Bourne Police Department Boxborough Police Department Boxford Police Department Boylston Police Department Braintree Police Department Brewster Police Department Bridgewater Police Department Brimfield Police Department Brockton Police DepartmentOfficial web site accessed 23 October 2014 Brookfield Police Department Brookline Police Department Buckland Police Department Burlington Police Department Cambridge Police DepartmentOfficial web site accessed 23 October 2014 Canton Police Department Carlisle Police Department Carver Police Department Charlemont Police Department Charlton Police Department Chatham Police Department Chelmsford Police Department Chelsea Police DepartmentOfficial web site accessed 23 October 2014 Cheshire Police Department Chester-Blandford Police Department (the second dual-town agency created in Massachusetts — after the Hardwick-New Braintree Police Department — the Chester Police Department began providing law enforcement services to Blandford in July 2018 and was renamed to the "Chester-Blandford Police Department" in December 2019) Chesterfield Police Department Chicopee Police Department Chilmark Police Department Clarksburg Police Department Clinton Police Department Cohasset Police Department Colrain Police Department Concord Police Department Conway Police Department Cummington Police Department Dalton Police Department Danvers Police Department Dartmouth Police Department Dedham Police Department Deerfield Police Department Dennis Police Department Dighton Police Department Douglas Police Department Dover Police Department Dracut Police Department Dudley Police Department Dunstable Police Department Duxbury Police Department East Bridgewater Police Department East Brookfield Police Department East Longmeadow Police Department Eastham Police Department Easthampton Police Department Easton Police Department Edgartown Police Department Egremont Police Department Erving Police Department Essex Police Department Everett Police Department Fairhaven Police Department Fall River Police DepartmentOfficial web site accessed 23 October 2014 Falmouth Police Department Fitchburg Police DepartmentOfficial web site accessed 23 October 2014 Foxborough Police Department Framingham Police Department Franklin Police DepartmentOfficial web site accessed 22 December 2014 Freetown Police Department Gardner Police Department Georgetown Police Department Gill Police Department Gloucester Police Department Goshen Police Department Gosnold Police Department Grafton Police Department Granby Police Department Granville Police Department Great Barrington Police Department Greenfield Police Department Groton Police Department Hadley Police Department Halifax Police Department Hamilton Police Department Hampden Police Department Hancock Police Department Hanover Police Department Hanson Police Department Hardwick-New Braintree Police Department (the first dual-town agency created in Massachusetts, the Hardwick Police Department began providing law enforcement services to New Braintree in July 2014 and was shortly thereafter renamed to the "Hardwick-New Braintree Police Department") Harvard Police Department Harwich Police Department Hatfield Police Department Haverhill Police DepartmentOfficial web site accessed 23 October 2014 Hawley Police Department Heath Police Department Hingham Police Department Hinsdale Police Department Holbrook Police Department Holden Police Department Holland Police Department Holliston Police Department Holyoke Police DepartmentOfficial web site accessed 23 October 2014 Hopedale Police Department Hopkinton Police Department Hubbardston Police Department Hudson Police Department Hull Police Department Huntington Police Department Ipswich Police Department Kingston Police Department Lancaster Police Department Lanesborough Police Department Lakeville Police Department Lawrence Police DepartmentOfficial web site accessed 23 October 2014 Lee Police DepartmentFormer Lee Police Chief Joseph Buffis pleads not guilty to a dozen federal charges; by Andrew Amelinckx, 4 September 2104, Berkshire Eagle Leicester Police Department Lenox Police Department Leominster Police Department Leverett Police Department Lexington Police Department Leyden Police Department Lincoln Police Department Littleton Police Department Longmeadow Police Department Lowell Police DepartmentOfficial web site accessed 23 October 2014 Ludlow Police Department Lunnenburg Police Department Lynn Police DepartmentOfficial web site accessed 23 October 2014 Lynnfield Police Department Malden Police DepartmentOfficial web site accessed 23 October 2014 Manchester-by-the-Sea Police Department Mansfield Police Department Marion Police Department Marblehead Police Department Marlborough Police DepartmentOfficial web site accessed 23 October 2014 Marshfield Police Department Mashpee Police Department Mattapoisett Police Department Maynard Police Department Medfield Police Department Medford Police DepartmentOfficial web site accessed 23 October 2014 Medway Police Department Melrose Police DepartmentOfficial web site accessed 23 October 2014 Mendon Police Department Merrimac Police Department Methuen Police Department Middleborough Police Department Middlefield Police Department Middleton Police Department Milford Police Department Millbury Police Department Millis Police Department Milleville Police Department Milton Police Department Monson Police Department Montague Police Department Monterey Police Department Nahant Police Department Nantucket Police Department Natick Police Department Needham Police Department New Bedford Police DepartmentOfficial web site accessed 23 October 2014 New Marlborough Police Department New Salem Police Department Newbury Police Department Newburyport Police Department Newton Police DepartmentOfficial web site accessed 24 October 2014 Norfolk Police Department North Adams Police DepartmentOfficial web site visited 29 February 2020 North Andover Police Department North Attleborough Police Department North Brookfield Police Department North Reading Police Department Northampton Police DepartmentOfficial web site accessed 24 October 2014 Northborough Police Department Northbridge Police Department Northfield Police Department Norton Police Department Norwell Police DepartmentPolice identify two killed in Norwell motorcycle crash, by Neil Simon, 25 July 2014, The Patriot Ledger Norwood Police Department Oak Bluffs Police Department Oakham Police Department Orange Police Department Orleans Police Department Otis Police Department Oxford Police Department Palmer Police Department Paxton Police Department Peabody Police DepartmentOfficial web site accessed 24 October 2014 Pepperell Police Department Pelham Police Department Pembroke Police Department Peru Police Department Petersham Police Department Phillipston Police Department Pittsfield Police DepartmentOfficial web site visited 29 February 2020 Plainfield Police Department Plainville Police Department Plymouth Police Department Plympton Police Department Princeton Police Department Provincetown Police Department Quincy Police DepartmentAppeals denied for Quincy police sergeants seeking promotions, by Patrick Ronan, 12 August 2014, The Patriot Ledger Raynham Police Department Randolph Police Department Reading Police Department