|“|| Spencer: Why does everything lead back to Radley?
Toby: Cause Radley is where everyone goes to leave their secrets. Wilden, Mona, CeCe-
— Spencer and Toby, Who's In The Box?
Radley Sanitarium is a mental institution where Mona Vanderwaal was sent, after her reveal as A. Spencer Hastings was also housed there for a time, being placed in the same room as Mona was, and Marion Cavanaugh was also there for some time before the start of the series. It was a key place and location in Season 3.
The Radley Sanitarium is located in the fictional Darkette County, Pennsylvania. It plays into the series when Mona is in this facility, but we can guess it has something to do with the story Alison tells about the girl who was sent to a mental institution after killing her twin sister.
The first time in the series the name "Radley Sanitarium" is referenced in "The First Secret." The Liars are walking across a street when they think they see someone in the window of a haunted house. As they walk away, the door opens and the camera cuts to a taxi parked in front of the house with the words "Radley Sanitarium" on the side of it.
Mona is sent to Radley Sanitarium after revealing that she is "A" in "UnmAsked." She is visited by someone in a red coat, similar to that of Vivian Darkbloom's: as we'll learn in Season 3, that someone was CeCe Drake. However, it has been stated by Marlene King that this was a hallucination, and these events did not actually occur.
- Hanna has been visiting Mona at Radley for answers. Mona remains quiet the first few times Hanna visits. She finally talks to Hanna. ("Blood Is The New Black")
- Mona freaks out when Caleb comes to Radley to visit. He tells her that she better not do anything to hurt Hanna. She then starts screaming and throws a table across the room. This results in her doctor making the decision to allow no visitors. ("Kingdom of the Blind")
- In the episode "Crazy," Mona leaves her room while Hanna and Aria are visiting and runs to the Children's Ward, where she brushes some dolls' hair.
- In the mid-season finale, "The Lady Killer", Mona breaks out of Radley by dressing as a nurse and flashing the guard a fake ID (taken from Hanna in an earlier episode).
- In the episode "She's Better Now," Mona is released.
- In episode "Out of Sight, Out of Mind," Spencer Hastings was placed in Radley after she was found wandering around, covered in blood, and in a catatonic state. She was identified as "Jane Doe" when a hiker found her.
- In "Will The Circle Be Unbroken?," An orderly, E. (Eddie) Lamb reveals to Spencer that Toby's mother, Marion Cavanaugh was a patient at Radley.
- In the episode "A DAngerous GAme", Spencer is released from Radley. Mona tells The Liars that she was shown how to get in and out of Radley during her stay.
- In "Cat's Cradle" Spencer and Toby go back to Radley to investigate what really happened to Toby's mother the day she died.
- In "The Guilty Girl's Handbook," Spencer goes back to Radley to ask Eddie Lamb about the inconsistencies of Dectective Wilden's police report for Marion Cavanaugh's death.
- In "Into the Deep," after Mona confesses to shooting Wilden, she is sent back to Radley.
- In "The Mirror Has Three Faces," Mona has a psych evaluation with Wren in her room. She doesn't tell him anything, because she doesn't trust him anymore. Veronica Hastings goes to Radley and threatens her. Jessica DiLaurentis tells Hanna and Spencer that CeCe Drake once checked into Radley dressed as Alison.
- Mona is again released from Radley in "Now You See Me, Now You Don't."
- In "Close Encounters" it's revealed that Alison's mother, Jessica DiLaurentis, was on the board of trustees before she died.
- The girl revealed in Ali's grave is former patient Bethany Young. ("Miss Me x 100")
- Eddie Lamb gives Ezra a drawing Bethany made at Radley. ("Run Ali Run,")
- Aria starts volunteer work at Radley to find out about Bethany and finds her roommate, Big Rhonda. ("The Silence of E. Lamb")
- Rhonda tells Aria that Bethany was given gifts from Jessica and figured it had something to do with Toby's mother's death. ("Scream For Me")
- Spencer and Mona break into Radley disguised as nurses to find information on Bethany Young and to see if there's a connection between her and Alison. (Taking This One to the Grave)
- Elizabeth Mainway - Owner
- Jessica DiLaurentis - Board of Trustees (before her death)
- Dr. Louis Palmer - Formerly
- Eddie Lamb - Nurse; formerly
- Nurse Lisa
- Nurse Sybil - Mentioned by Mona
- Dr. Wren Kingston - Volunteer Doctor
- Aria Montgomery - Volunteer
- Marion Cavanaugh - Before her death
- CeCe Drake - Checked in once, as Alison DiLaurentis
- Mona Vanderwaal - Formerly; was admitted twice previously for 7 months (April 2011 - early November 2011) and a few days after she claimed to have killed Wilden.
- Spencer Hastings - Formerly (1 week)
- The Fragile Patient - Around when Marion was a patient.
- Bethany Young - Before her death; Escaped the day Alison disappeared.
- Big Rhonda - Bethany Young's ex-roommate at Radley.
- Donna - Blonde that rips up her art work in The Silence of E. Lamb
- Nicky - Girl being hauled away while aria comes to visit Mona
- In the books, Radley was a place for "troubled" kids and now it is a hotel.
- In the TV show Mona Vanderwaal and Spencer Hastings go to Radley. While in the books neither of them do because Radley is shut down before Alison DiLaurentis (Book Character) goes missing.
- In the books only Courtney DiLaurentis (Book Character) is a patient at Radley
- Janel Parrish (Mona Vanderwaal) revealed in an interview that the Radley Sanitarium plays a significant role in Season 3.
- The Radley Sanitarium also could come into play more if Courtney DiLaurentis exists.
- Named after the character, Boo Radley, from the novel To Kill A Mockingbird, which makes an appearance in the series as book Fitz's class reads their junior year.
- Radley Santitarium was established in 1931.