Jane Maria Swift (born February 24, 1965) is an American politician and nonprofit executive who served as the 69th lieutenant governor of Massachusetts from 1999 to 2003 and, concurrently, as acting governor from April 2001 to January 2003. She was the first woman to perform the duties of governor of Massachusetts. At the time she became acting governor, Swift was 36 years old, making her the youngest female governor in U.S. history.

Swift grew up in a large extended family in North Adams, Massachusetts. Her maternal grandmother immigrated to the United States from northern Italy after World War I, and her paternal grandfather was a Plymouth, Massachusetts native with roots in Ireland as well as on the Mayflower. She learned politics from her father, Jack Swift, who ran the family HVAC business and was active in the Berkshire County Republican Party. Swift's mother, a graduate of North Adams State College, was a teacher in area public and parochial schools. Swift attended North Adams public schools, and in 1987 graduated from Trinity College in Hartford, Connecticut, with a degree in American studies. During her college years, Swift held work-study jobs in the college dining hall and with the Religion & Philosophy Department, played on the women's rugby team, and was a member of the Kappa Kappa Gamma sorority.

In 1990, at the age of 25, Swift was the youngest woman ever elected to the Massachusetts Senate. She served the Berkshire, Hampshire, Franklin, and Hampden Massachusetts Senate district from 1991 to 1997 and was active in education reform. She was instrumental in the passage of the Education Reform Act of 1993, which created the Massachusetts Comprehensive Assessment System, one of the nation's first statewide programs for quantifying academic performance.

According to Governor Bill Weld's chief of staff, "She was among the best, if not the best of senators." It was in this capacity that she developed political themes of increased accountability, smaller government, fiscal responsibility, and reforming education and social services.

In 1996, rather than seek re-election to the Senate, Swift was the Republican nominee for United States Congress in Massachusetts's 1st congressional district. She lost to a popular two-term incumbent Democratic Congressman, John Olver, by four points.

Swift went on to serve as an executive with the Massachusetts Port Authority, and was later appointed by Governor Weld as Massachusetts' consumer affairs secretary in 1997. She served in that post until she was elected lieutenant governor in 1998, in a campaign that was notable not only for her relative youth but also for the fact that she was pregnant with her first child, Elizabeth, whom she gave birth to just a few weeks before election day.

During her time as lieutenant governor, Swift faced significant scrutiny for her choices as a high-profile working mother. She was especially criticized for using staff members to watch her daughter, and for her Massachusetts State Police detail's use of a helicopter to avoid Thanksgiving traffic en route to her home in The Berkshires when her baby was sick. In an ethics ruling that Swift herself requested, she was found to be in violation of state guidelines for the babysitting and she paid a fine of $1250, but she was cleared of wrongdoing on the question of the use of the helicopter and on allegations that staffers helped her move from one Boston-area apartment to another. Twenty years later, Boston reporter Joanna Weiss reflected on the gender bias that faced Swift throughout her tenure.

Swift became acting governor of Massachusetts in April 2001 when Governor Paul Cellucci was appointed United States Ambassador to Canada by President George W. Bush. In Massachusetts, a vacancy in the governor's office is filled by the lieutenant governor, who serves as acting governor without formally taking on the office. She was pregnant with twins at the time, and became the first sitting governor in U.S. history to give birth when her twin daughters, Lauren and Sarah Hunt, were born one month into her term of office. She made national headlines when she continued to exercise executive authority during her maternity leave, including chairing a meeting of the Massachusetts Governor's Council by teleconference while on bed rest for preterm labor. Members of the Democratic-controlled Governor's Council objected, contesting her authority to convene official meetings while on leave.