Physical accessibility on the Massachusetts Bay Transportation Authority (MBTA or "the T") system is incomplete but improving, with accessibility on all buses (including the Silver Line), all Orange Line stations, all but 2 Red Line stations, and all but 2 Blue Line stations. As is true for most mass transit systems, much of the Boston subway and commuter rail lines were built before wheelchair access was a requirement. The Boston system underwent significant expansion in the 1980s and 1990s, and all the new facilities are ADA compliant. The MBTA has also refurbished many stations, and these too are accessible. More improvements are in progress or expected as part of planned construction.
In addition, on April 4, 2006 the MBTA announced the settlement of a class-action lawsuit, Joanne Daniels-Finegold, et al. v. MBTA, under which "the T will undertake major improvements in equipment, facilities and services that promise to enhance accessibility for people with disabilities while improving service for all T passengers. ...approximately $310 million in funds will be programmed into the T's Capital Investment Program to improve services and infrastructure."
Accessibility on the T generally means that some combination of elevators and wheelchair ramps connect the street and station platform. The MBTA provides recorded elevator, wheelchair lift and escalator status updates by telephone: 1-617-222-2828 or 1-800-392-6100; in case of questions that are not answered by the recorded telephone service, customer service representatives are available at 617-222-3200.
- All stations on the Orange Line and Red Line are accessible and all have high level platforms on the same level as train car doors, except for Wollaston on the Red Line proper and Valley Road on the Mattapan Line (see below).
- Stations on the Blue Line are wheelchair accessible except for Government Center and Bowdoin. All Blue Line stations have high level platforms which should be on the same level as train car doors, although in a few stations, the actual alignment between the floor of the train and the station platform may be sufficiently mismatched that a wheelchair user will need to ask the train crew for assistance.
- Bowdoin was originally scheduled to be closed permanently in 2008, but has been kept open due to lack of funds for an additional entrance to Government Center that would have removed some of the need for Bowdoin. As of 2011, design work is ongoing for a complete rebuild of Government Center station, including complete wheelchair access to all platforms. Bowdoin will remain open during the Government Center rebuild, but likely will be closed permanently afterwards. For more details, see the article on Government Center and the Red Line Blue Line Connector project described there.
- The Green Line runs trolley cars, and only newer vehicles (MBTA Type 8, also called "Breda") have low-floor, wheelchair accessible entrances; these entrances are only wheelchair accessible at the minority of stations that have matching raised platforms, although a few stations that lack such platforms have been equipped with portable lifts or wayside ramps.
- The low-floor wheelchair access is by means of a bridge plate that extends from the vehicle to the platform (which requires that the platform have been upgraded to match). This is much less demanding upon the operator and requires much less time than use of the portable lifts. However, it is often necessary to remind the driver of the need for the ramp to be extended when a wheelchair passenger has reached the desired destination; the blue button with the universal disabled symbol located inside near the door is for this purpose.
- Low-floor Type 8 vehicles are now running on all branches after a track upgrade on the D branch to accommodate them without danger of derailment. With this upgrade, low-floor streetcar service is available on all branches of the Green Line, and all 2-car trains are supposed to contain at least one low-floor streetcar, although as noted above, this is actually usable for wheelchair access only at a minority of stations; single-car trains may still lack low-floor access, and in actual practice, occasional 2-car all-high-floor trains do run in service.
- Access to the older high-floor vehicles requires either a portable lift or a wayside ramp equipped with a bridge that can be lowered into the vehicle through one of the doors. Use of the portable lifts to load and unload wheelchair-using passengers requires considerable physical effort from the operator (usually the driver) and may require several minutes.
- The Mattapan portion of the Red Line run runs older, high floor PCC trolley cars. Wheelchair ramps with hinged metal bridges have been installed at each station except for Valley Road, which has a long staircase from the platform to street level, which makes the platform itself inaccessible for wheelchair users.
As of July 2013[update], 104 out of 138 MBTA Commuter Rail stations (75%) are accessible. Five lines are entirely accessible: the Greenbush Line, Plymouth/Kingston Line, Middleborough/Lakeville Line, Fairmount Line, and Needham Line, while the other lines have a mix of accessible and non-accessible stations. All stations built or rebuilt since about 1987 are accessible, many older stations have been retrofitted and several other stations are currently being rebuilt for accessibility.
Of those stations that have wheelchair access, some only have a short elevated platform that serves one or two cars. These "mini-high platforms" are usually located at the end of the station away from Boston, allowing them to be served by the car nearest the locomotive. They represent most accessible stations on the Franklin Line, Needham Line, Framingham/Worcester Line, Fitchburg Line, Lowell Line, Haverhill Line, and Newburyport/Rockport Line, as well as several stations on the Providence/Stoughton Line and Fairmount Line. The limited-use stations at Foxboro (used for special events and game day service) and Buzzards Bay and Hyannis (used for the CapeFLYER service run with MBTA trains) have mini-high platforms as well.
Some commuter rail stations, mostly newer stations and those in larger cities, do have full-length high-level platforms that allow for accessible boarding on all cars. (The standard MBTA high-level side platform is 12 feet wide and 800 feet long, capable of fully handling a 9-car train – longer than any trainset currently in service. Some stations, including Forest Hills and Route 128, have Amtrak-style 1050-foot 12-car platforms.) The MBTA builds full-length high-level platforms at most new stations, and ultimately plans to build full-length high-level platforms at most stations except those requiring clearance for freight trains. Full-length platforms allow automatic power doors to be used, which allows passengers to board at all doors and thus speeding boarding times. High-level platforms are in place at all stations on the Greenbush Line, Plymouth/Kingston Line, and the Middleborough/Lakeville Line (all three of which have power doors in use), as well as all stations on the Fairmount Line except Fairmount and Readville. Other stations with full-length high-level platforms include:
- South Station
- Back Bay (all tracks except those serving the Framingham/Worcester Line, which only have a mini-high)
- Forest Hills
- Route 128
- T.F. Green Airport
- Wickford Junction
- North Station
- Littleton/Route 495
- Anderson RTC
Several other stations have high-level platforms that can accommodate several cars, but not necessarily all cars on a train. The Malden Center and Oak Grove platforms are shorter because they were built to be used as Orange Line platforms, as the line was to replace Haverhill Line service as far as Reading. Shorter rapid transit trains only require platforms around 400 feet long.
- Malden Center
- Oak Grove (only used during Orange Line service disruptions)
The following stations are currently being rebuilt for accessibility:
- South Acton (full-length high-level)
- Sharon (mini-high)
- Yawkey (already had a mini-high serving one track; new station will have high-level platforms serving both tracks)
The following new stations are under construction (or in final design) with full-length high-level platforms:
Center island stations
Most MBTA subway stations have side platforms but a few have island platforms. The latter make it easier for wheelchair passengers to reverse direction, either because they missed a stop, or because the elevator on one side of a station is out of service. Some of these stations are not accessible to wheelchair users wishing to leave or enter them. Center island MBTA subway stations are:
- Bowdoin (currently, no elevator access is available to or from this platform, so wheelchair users can only use it to transfer between inbound and outbound trains; this station will never be modernized; it was scheduled to be closed permanently once the MBTA started to run 6-car trains on the Blue Line in 2008, but the closing has been delayed due to lack of funds to add another entrance to Government Center)
- Government Center (currently, no elevator access is available to or from this platform, so wheelchair users can only use it to transfer between inbound and outbound trains; this station is scheduled to be rebuilt to include handicapped-accessibility within the next few years; the rebuild was originally supposed to add an entrance that would have reduced the need for Bowdoin, but no funds have been available for this addition)
- North Station (inbound track: in this case, the island platform is between the Green Line and Orange Line inbound tracks; elevators provide access to the outbound tracks of both lines)
- Government Center (three track island: the platform is a distorted triangle between the southbound and two northbound tracks, of which one is a through track and the other is a turnaround loop that receives southbound trains from Haymarket and sends them back north; this platform is not wheelchair-accessible, but a rebuild is scheduled to start in 2013.)
- Park Street (2 islands, one between the two southbound tracks and one between the two northbound tracks, the outer of which also has a side platform, connected to the island platform by an accessible grade crossing. Separate elevators are available from the Red Line island platform to the southbound and northbound Green Line elevators, after a project completed in 2012. Elevators connecting the Green Line platforms to an underground connecting passage provide a redundant route in case of an elevator outage.
- Kenmore (2 islands, one between the two outbound tracks and one between the two inbound tracks)
- All Green Line Extension stations will have center island platforms, including the new Lechmere station
- all stations between Oak Grove and Community College, including the under-construction Assembly Square station
- all stations between Back Bay and Forest Hills
- Harvard (actually a hybrid island/side platform station, in which both platforms are on the west side of their respective tracks; platforms are connected by a sequence of two ramps that run downhill from the outbound platform to the lower turnstile area and thence to the inbound platform)
- Park Street (has both island and side platforms; only the island platform has elevator access; see description under Green Line above)
- JFK/UMass (there are separate islands for each branch of the Red line)
- Savin Hill (last center island on Ashmont branch)
- All stations between North Quincy and Braintree; however, Wollaston is currently not accessible. Since the July 2012 closure of the parking garage, Quincy Center is only partially handicapped accessible, with no wheelchair access from the Burgin Parkway entrance.
All bus service, including the Silver Line, is accessible.
The T also has paratransit program, called The Ride which provides lift-equipped vans to transport people who cannot use general public transportation because of a physical, cognitive or mental disability, including those who use wheelchairs.
Blind and visually impaired
The MBTA states that "Service animals are always welcome on MBTA vehicles and in MBTA stations during all hours of service. The service animal should be kept out of the aisles as much as possible and under your control at all times." 
Some train stations have yellow detectable warning strips with truncated domes running in a two-foot (60 cm) band along the edge of the platforms. Most Red, Orange, and Blue Line stations have these tactile strips; however, many less-used Green Line surface stops and commuter rail stations lack them.
Buses and trains are supposed to have either recorded announcements or driver announcements of station stops, but these announcements are sometimes muffled, inaudible, or omitted by automated systems. In the event that automated systems are not functioning properly, the vehicle driver or conductor is to announce stops over the public address system.
The MBTA has a TTY number for "T" information: (617) 222-5146. Many stations have TTY pay phones; the MBTA web site has a list.
The MBTA says it has reviewed its web site, http://www.mbta.com, using "the United States Section 508 guidelines and WCAG double AA guidelines, ... and made all required accommodations to help ensure that the site is accessible by users who rely on assistive technologies such as screen readers or other input mechanisms."
- 2006 MBTA press release on disability settlement Retrieved 2011 June 3
- "Ridership and Service Statistics". Massachusetts Bay Transportation Authority. 2010. Retrieved 29 December 2012. Since the publication date, accessible stations have been opened at T.F. Green Airport, Wickford Junction, Talbot Avenue, Four Corners/Geneva Ave, and Newmarket; Wedgemere and Littleton have been retrofitted for accessibility.
- "General Accessibility Facts". Massachusetts Bay Transportation Authority. Retrieved 29 December 2012.
- "The Customer Experience and Accessibility Features on Heavy Rail Trains and at Heavy Rail Stations (Red, Orange, Blue Lines)". Massachusetts Bay Transportation Authority. Retrieved 29 December 2012. "If the train′s stop announcement equipment isn′t working, the train personnel are required to announce the destination of the train."