Season 1 of 13 Reasons Why consists of thirteen episodes. All episodes, and the special 13 Reasons Why: Beyond the Reasons, were released on Netflix on March 31, 2017. The season is loosely based on a 2007 book of the same name by Jay Asher.
13 Reasons Why, based on the best-selling book by Jay Asher, follows teenager Clay Jensen (Dylan Minnette) as he returns home from school to find a mysterious box with his name on it lying on his porch. Inside he discovers a group of cassette tapes recorded by Hannah Baker (Katherine Langford) -his classmate and crush-who tragically committed suicide two weeks earlier. On tape, Hannah unfolds an emotional audio diary, detailing the thirteen reasons why she decided to end her life. Through Hannah and Clay's dual narratives, 13 Reasons Why weaves an intricate and heartrending story of confusion and desperation that will deeply affect viewers. 
Cast and Characters
|"Tape 1, Side A"|
|As the school mourns the death of Hannah Baker, her friend, Clay, receives a box of 13 cassette tapes, she recorded, explaining the reasons why she committed suicide, before she committed suicide. This episode explains and explores her first reason, Justin.|
| "Tape 1, Side B"
|Hannah makes friends with two other new students at Liberty High School, Jessica and Alex. Justin doesn't show up at school. Hannah's mother, Olivia Baker, finds something of Hannah's that proves to be trouble. Jessica is the second reason.|
|"Tape 2, Side A"|
|Jealousy, rumors and gossip, make a vigorous mess of Hannah's relationships. Alex talks to Clay about his struggles with guilt and regret over Hannah. Bryce, Justin, Zach and Montgomery pressure Clay into a drinking contest with Alex. Alex is the third reason.|
| "Tape 2, Side B"
|Hannah thinks someone is stalking her and enlists Courtney's help to set a trap. Olivia confronts the school's principal. Clay strikes back at Tyler, after learning Tyler ended Courtney and Hannah's friendship with a photograph. Tyler is Hannah's fourth reason.|
|"Tape 3, Side A"|
|Hannah and Clay connect at the school dance. But a rumor Courtney started ruins her reputation. Clay takes Courtney to visit to Hannah's grave, reminding her she made a mistake that helped Hannah get to where she is now. Courtney is Hannah's fifth reason.|
| "Tape 3, Side B"
|Hannah's date on Valentine's Day goes abruptly wrong after Marcus secretly takes on a dare. Alex gets into a fight with Montgomery over almost being hit with his car and underlying more and they both face the school board's decision. Marcus is Hannah's sixth reason.|
|"Tape 4, Side A"|
|Zach sabotages Hannah's social life during a class project. Clay starts to have nightmares and delusions abut Hannah, confiding in Tony that he can't get through listening to her voice and what she's been though. Zach is Hannah's seventh reason.|
| "Tape 4, Side B"
|Hannah gets to know Ryan, inspired by him writes some personal poetry which Ryan prints in a magazine without her permission. Tony goes rock climbing with Clay whilst helping him sort out his demons. Ryan is Hannah's eighth reason.|
|"Tape 5, Side A"|
|Hannah witnesses Jessica be raped by Bryce at a party. Clay tries to rise to the surface with Justin after understanding that Justin knows about Bryce and Jessica, but is warned by Marcus that the worse is yet to come.|
| "Tape 5, Side B"
|A traumatized Hannah gets a ride home from Sheri, on the way home they have an accident. Jessica's behaviour becomes increasingly erratic. Clay learns the truth behind the tragedy of Jeff Atkins from Sheri. Sheri is Hannah's tenth reason.|
| "Tape 6, Side A"
|As events start to come to an understanding, Tony drives Clay up to a space at night where he can listen to his tape, which becomes very heartbreaking for him to hear as he imagines saying words that could save Hannah's life. Clay is Hannah's eleventh reason, but she apologizes for him being on the list, as it wasn't actually his fault, she only wanted him to be a part of her story.|
| "Tape 6, Side B"
|Hannah goes from witnessing Bryce rape Jessica to being raped by Bryce and at this point she thinks her life is worth nothing, a pissed off Clay gets a confession out of Bryce and looks to seek further justice after recording it. Bryce is Hannah's twelfth reason.|
| "Tape 7, Side A"
|This describes and explores the final day of Hannah Baker's life. Hannah seeks help from Mr. Porter, but he doesn't help but rather tells her to move on or get the police involved. Clay plays a 14th tape he recorded for Hannah and gives him a copy. Clay walks Mr. Porter through everything that happened the day after Hannah's trauma before giving him the tapes he received including number 14, giving out enough evidence to put Bryce in jail for Jessica and Hannah. Some students go to their deposition and come clean.|
- The first season of 13 Reasons Why has an ending which the producers said they left open for another season, possibly for what happens with Alex Standall, Tyler Down, Bryce Walker and other characters.