MCI-Cedar Junction is one of two (the other one being Souza-Baranowski Correctional Center) maximum security prisons for male offenders in the Commonwealth of Massachusetts.

In 1955, Richard Cardinal Cushing, Archbishop of Boston, built Our Lady of the Ransom Chapel at the center of the prison.

As of June 2009, MCI-Cedar Junction serves as the reception and diagnostic center, which receives all new male court commitments for the Commonwealth of Massachusetts' Department of Correction.

In the 2020 film, Spenser Confidential, the film's titular protagonist was sent to "Walpole" for 5 years after pleading guilty to harassment and assault on his Boston Police commanding officer John Boylan, who is revealed to be a dirty cop involved in a drug conspiracy.

First phase plans to start around the summer of 2022, moving any newly sentenced men to the Souza-Baranowski Correctional Center, a maximum security prison located in Lancaster, Massachusetts.