The Commonwealth of Massachusetts is governed by a set of political tenets laid down in its state constitution. Legislative power is held by the bicameral General Court, which is composed of the Senate and House of Representatives. The governor exercises executive power with other independently elected officers: the Attorney General, Secretary of the Commonwealth, and Auditor. The state's judicial power rests in the Supreme Judicial Court, which manages its court system. Cities and towns act through local governmental bodies to the extent that they are authorized by the Commonwealth on local issues, including limited home-rule authority. Although most county governments were abolished during the 1990s and 2000s, a handful remain.

Massachusetts' capital city is Boston. The seat of power is in Beacon Hill, home of the legislative and executive branches. The Supreme Judicial Court is in nearby Pemberton Hill.

Massachusetts has 151 departments or agencies and over 700 independent boards and commissions.^[1] The head of the state's Executive Branch is by law the Governor, but it also has two types of executive officials that do not fall in the Governor's control. Constitutional officers are the elected officials specified by the state constitution, while independent agencies are created by statute and the governor exercises only indirect control through appointments.^[2]

The state legislature is formally known as the Massachusetts General Court, reflecting its colonial-era judicial duties. It has two houses: the 40-member Senate and the 160-member House of Representatives. Members of both houses have two-year terms. The Speaker of the House presides over the House of Representatives and controls the flow of legislation. The President is the presiding officer of the Senate.

The General Court is responsible for enacting the state's laws. A bill signed by the governor, or passed by two-thirds of both houses over his or her veto, becomes law. Its session laws are published in the Acts and Resolves of Massachusetts, which are codified as the General Laws of Massachusetts. On June 9, 2017, S&P Global Ratings downgraded Massachusetts' bond rating to AA (the third-highest tier) due to the legislature's inability to replenish the state's rainy day fund in the face of above-average economic growth.^[7]

The judiciary is the branch of the government that interprets and applies state law, ensures equal justice under law, and provides a mechanism for dispute resolution. The Massachusetts court system consists of the Supreme Judicial Court, the Appeals Court, and seven trial-court departments.

Only the southeastern third of the state has county governments; in western, central, and northeastern Massachusetts, traditional county-level government was eliminated during the late 1990s. District attorneys and sheriffs are elected by constituencies which mainly follow county boundaries, and are funded by the state budget.^[11][12] Sheriff's departments operate correctional facilities and perform service of process in the county.

Massachusetts shares with the five other New England states the New England town form of government. All land in Massachusetts is divided among cities and towns and there are no unincorporated areas, population centers, or townships. Massachusetts has four kinds of public-school districts: local schools, regional schools, vocational-technical schools, and charter schools.

Amendment Article 89 (LXXXIX) of the Massachusetts Constitution defines the powers of self-government that municipalities are entitled to. Additional powers, such as the ability to collect certain taxes, are delegated to municipalities under state law. The article requires that General Laws passed by the General Court apply to at least two municipalities. Special Laws that apply to only one municipality must be enacted in response to a home rule petition from that city or town, or with a two-thirds majority in the General Court, or for the purpose of establishing, disestablishing, or modifying municipal boundaries.^[17]

Proposition 2½ gives municipalities the right to state payment of municipal costs incurred as a result of any new state mandates implemented after January 1, 1981. Cities and towns can vote to accept a new mandate, or ask the Massachusetts State Auditor to determine the amount of funding owed; if the legislature does not provide that amount then ask the Massachusetts Superior Court for a ruling that grants the municipality an exemption from complying with unfunded mandates.^[18]

Massachusetts is known for its progressive politics, and is a stronghold of American Liberalism and the Democratic Party. In a 2018 Gallup poll Massachusetts was the state with the highest percentage of its population identifying as liberal and the lowest percentage identifying as conservative, at 35% and 21% respectively.^[19] This and the high profile of well known politicians from Massachusetts such as the Kennedy family has led to the derogatory political phrase "Massachusetts Liberal".

• 48 out of 50 for transparency of electoral candidate financial conflicts of interest (Pioneer Institute, 2019)^[20]
• B- for online access to government spending data (Public Interest Research Group, 2018)^[21]
• Corruption, out of 50 (higher numbers are better): 16 for convictions, 22 for convictions per capita, 49 as ranked by reporters, 39 in lacking stringent laws (2015)^[22]
• D+ for integrity (Center for Public Integrity, 2015)^[23]

• Outline of Massachusetts
• Index of Massachusetts-related articles
• Politics of Massachusetts
• Law of Massachusetts
• Law enforcement in Massachusetts
• Judiciary of Massachusetts
• Courts of Massachusetts
• United States Congress
• United States congressional delegations from Massachusetts
• List of United States senators from Massachusetts
• Massachusetts's congressional districts
• List of United States representatives from Massachusetts
• State governments of the United States (comparison)