The Montachusett Regional Transit Authority (MART) is a public, nonprofit organization established under Chapter 161B of the Massachusetts General Laws to provide public transportation to the Montachusett Region.

MART is one of Massachusetts' 15 regional transit authorities[5] and provides public transportation to 21 communities[6] within the Montachusett region consisting of the cities of Fitchburg, Leominster and Gardner, and the towns of Athol, Ashburnham, Ashby, Ayer, Bolton, Boxborough, Hardwick, Harvard, Hubbardston, Lancaster, Littleton, Lunenburg, Royalston, Shirley, Sterling, Stow, Templeton, Westminster, and Winchendon.

MART also operates the parking areas at three MBTA Commuter Rail Fitchburg Line stations at North Leominster, Fitchburg Intermodal Transportation Center, and Wachusett, with local and intercity bus connections to all three stations.

MART has a working collaboration with Fitchburg State University to offer faculty, staff, and students free rides on the Fitchburg/Leominster fixed-route bus line.

[11] MART uses MBTA's CharlieCard smart card fare system.