The following events took place in 1987:
- January 1 – Laura Palmer excuses herself upstairs to take cocaine, then overhears Leland asking Sarah why she has become so distant.
- January 3 – Laura writes in her diary about new developments since New Year's Eve. BOB interjects and mocks her insistence that he is only in her head, and warns that a place is being saved for her in hell.
- January 7 – Laura writes a poem in her diary, titled "In the Eyes of the Visitor."
- January 19 – Laura ditches school to rearrange the furniture in her room, and contemplates mailing a fantasy to Flesh World.
- January 20 – Laura spends the day with Johnny Horne, telling stories to entertain him. Afterward, she opens a P.O. box.
- July 22 – On her sixteenth birthday, Laura Palmer discovers she is seven-and-a-half weeks pregnant.
- August 10 – Laura Palmer has an abortion. In her diary she writes a message to her unborn child.
- August 20 – Laura has a nightmare where she floats around her high school, invisible. When we awakens, she sees BOB at her window.
- August 21 – Dale Cooper is assigned to a drug interdiction joint task force with the Drug Enforcement Administration.
- August 23 –
- Josie Packard visits the Double R Diner, upset over workers at the sawmill mocking her poor English. Laura offers to give her lessons and agrees to meet the next Monday.
- Laura makes the first Meals on Wheels run, delivering dinner to Mrs. Tremond and Harold Smith. She then spends the evening babysitting Johnny Horne.
- August 24 – In a tape recording, Cooper discusses his new DEA colleagues and ponders telling them about his new investigative method based on the teachings of the Tibetan monk Gumm.
- August 26 – After applying Gumm's teachings, Cooper tells Diane in a tape that he believes Lee Harvey Oswald was not working alone and Jack Ruby may be in hiding in Peru.
- August 30 – Date of an entry torn out of Laura's original diary.
- August 31 – After rereading the previous day's entry, Laura writes in her diary about her misery at the state of her life, and about a dream where she saw BOB kill Waldo at Jacques Renault's cabin.
- September 2 – Dale Cooper and Dennis Bryson are assigned by the DEA to act as buyers in a sting operation in Tijuana, Mexico.
- September 4 – Cooper and Bryson make contact with their mark, but he refuses to deal with both of them. Bryson attends the meeting alone and does not report back at the arranged time.
- September 9 – Through coercion, Cooper learns from two dealers that Bryson is being held at a ranch outside the city, and borrows their vehicle. Above the compound, he formulates a plan to break him out.
- September 10 –
- September 26 –
- September 27 – The Twin Peaks Post publishes an article by Cyril Pons on Packard's accidental death.
- Investigators determine that the boat explosion was the result of a leak on the fuel line. Packard's will leaves the Packard Sawmill and his other businesses to his wife, Josie.
- November 9 – Dale Cooper informs Diane that, to his dread, he must undergo a dental check-up as part of a drug interdiction effort in Oakland.
- November 15 – Cooper dictates to Diane that, the previous night, he dreamed about his mother feeding him several bowls of sugary cereal.
- November 18 – Cooper informs Diane that he has successfully arranged a drug deal with the dentist he is investigating, and also that he has six cavities.
- November 23 – Cooper reports to Diane that the dentist is in custody.
- November 29 – Dr. Lawrence Jacoby conducts a psychiatric evaluation of Nadine Hurley.
- Unknown date – Leo Johnson is arrested for drunk and disorderly conduct.
- December 15 – Dale Cooper leaves the DEA-FBI joint task force.
- December 20 – Cooper tells Diane he is grateful to be off the task force.