January 2012 ​

- 1st. Marshall visits his fathers grave in Minnesota to continue their tradition of tailgating. Eventually many people including Marshall's brothers show up and they all watch the Vikings vs. Bears football game, Back in New York Lily is surprised to see her dad. After hearing she was pregnant he drove all night to get to her. [713 Tailgate]​

- 2 weeks later. Marshall and Lily move into their house in the suburbs and after having a power cut Lily's dad Mickey helps them restore power and comes up with the idea for his only hit board game, "Lites Out". [Two weeks after January 1st, 714 46 Minutes]​

February 2012

- Marshall and Lily have a housewarming party. [715 The Burning Beekeeper]

  -11th. Barney meets Quinn while being a wingman for Ted. [716 The Drunk Train]​ 

- 12th. Lily & Marshall and Robin & Kevin go to a Valentines couples weekend in Vermont at which Kevin proposes to Robin, Barney and Ted go on the Drunk Train for the first time but end up falling asleep. [716 The Drunk Train]
- 13th. Robin tells Lily and Marshall about Kevin's proposal and her infertility, Barney and Ted go on the Drunk Train again but strike out. They end up crashing at Lily and Marshall's home on Long Island. [716 The Drunk Train]
- 14th. Valentines Day. Barney and Ted discover the secret of the Drunk Train is to be drunk while riding it but Barney, distracted by Quinn, leaves the girl he's with, Robin tells Kevin about her being infertile and never wants kids and eventually they break up, Ted tells Robin he loves her. [stated to be Valentines Day, 716 The Drunk Train]
- 15th. Robin leaves on a work trip to Russia​ telling Ted they will talk about getting back together when she gets back, Barney finds out about Lily and Marshall's long term bets. [717 No Pressure]​

- Robin arrives back from Russia and her and Ted asks Robin if she loves him. She says no and they decide to not get back together and just remain friends, Robin moves out of the apartment. [717 No Pressure]​

- After being played by Quinn and being hurt by her actions. Barney and her reconcile and have coffee. [718 Karma]

- Ted moves out of the apartment and gives it to Lily & Marshall. [718 Karma]​

March 2012

- Barney is not seen for a couple of weeks. The gang meets Quinn for the first time and Barney and Quinn mess with them. Barney and Quinn move in together. [719 The Broath]​

- Robin is promoted to co-anchor with Sandy Rivers at Worldwide News. [719 The Broath]​

- Worried about being back on air again Robin gets really drunk. The following morning Barney gives her his Stinson Hangover Fixir Elixir to help her feel better. [918 Rally]

April 2012

- Trilogy Time 2012. Ted reflects back on the past Trilogy times and is disappointed about where he is in his life. [720 Trilogy Time]

- While Robin is doing a traffic report from a helicopter the pilot has a stroke and collapses. The whole of New York is glued to the TV as Robin is directed how to fly a helicopter and land it. The incident makes her famous and she ends up meeting the mayor, going on Letterman and getting a sandwich named after her. She also gets text messaged by practically every person she'd ever met. [721 Now We're Even]

- Tracy meets Louis and they begin dating. He's Tracy's first boyfriend since Max died in 2005. [916 How I Met Your Mother Met Me. Tracy meets Louis on the same night as Robin flying the helicopter in 721 Now We're Even.]

May 2012

- Marshall and Lily have a baby shower. To avoid each other Robin arrives three hours early while Ted arrives three hours late. [722 Good Crazy]

- Barney takes Marshall to Atlantic City to unwind and while he's gone Lily goes into labour. He is able to make it back before she gives birth though and the gang welcomes Marvin Wait-for-it Eriksen into the world. [722 Good Crazy, 723 The Magician's Code Part One]

-  With the birth of his son Marshall quits smoking for good. [in 511 Last Cigarette Ever it's stated he quits when his son is born]

- Victoria leaves her fiance Klaus at the altar and re-unites with Ted. [724 The Magician's Code Part Two]

- Barney proposes to Quinn and she accepts. [724 The Magician's Code Part Two]

- Robin begins dating Nick. [They first met while she was dating Ted sometime in 2005-06 and then met again in April 2011, 621 Hopeless, 801 Farmhampton]

- Robin's dad moves to New York to be with his girlfriend (later wife) Carol, though Robin would not find out he was in New York till some time later. [Eight months before 813 Band Or DJ?]

June 2012

- Barney tells the gang his plan for the ultimate bachelor party, which he calls his bro mitzvah. [10 months before 822 The Bro Mitzvah]

Summer 2012

- Future Ted would later recall that this time was the summer of love with all four couples (Ted & Victoria, Lily & Marshall, Barney & Quinn and Robin & Nick) being happy. [802 The Pre-Nup]

October 2012

- Barney and Quinn break-up after realizing they don't trust each other after a lengthy discussion involving pre-nups. It begins what  Ted would later refer to the beginning of a period in the gangs lives called "The Autumn of Break-Ups" [Stated to be October in 802 The Pre-Nup]

- After a long search Lily and Marshall apoint Lily's father Mickey as Marvins nanny. [803 Nannies]

- For the first time in five months Lily and Marshall spend the whole day together with the gang. [804 Who Wants To Be A Godparent?]

- Marshall and Lily make Ted, Barney and Robin Marvin's legal guardians if anything should happen to them. [804 Who Wants To Be A Godparent?]

- Ted breaks up with Victoria after he makes him choose between marrying her or having Robin as a friend. [805 The Autumn of Break-Ups]

- Robin breaks up with Nick. [806 Splitsville]

- Ted's old boss, Hammond Druthers, offers him a job in Chicago. He initially declines but within six months he will change his mind. [909 Platonish]

- While trying to complete a challenge Barney has a chance encounter with Tracy, who encourages him to put all he is into pursuing Robin. Shortly afterwards he begins The Robin play, an elaborate plan to propose to her. [806 Splitsville, 909 Platonish]

November 2012

- After Quinn starts working at The Lusty Leopard strip club again Barney is forced to change strip clubs, and after a lengthy decision he chooses The Mouth Beach as his new strip club. [807 The Stamp Tramp]

- The week of November 19th. Marshall's lawfirm wins the case against Gruber Pharmaceuticals, who had polluted Frog Lake. Marshall is disappointed though when they only receive a settlement of $25,000. [Date given in 808 Twelve Horny Women]

December 2012

- The Ted-designed GNB building is officially completed. [808 Lobster Crawl]

- Baby Marvin Eriksen crawls for the first time but Ted is the first one to see it. [809 Lobster Crawl] 

- As part of his The Robin play to get engaged to Robin Barney starts dating Patrice. [809 Lobster Crawl]

- Marshall's mum Judy visits and sleeps with Lily's dad Mickey. [I said a bang, bang, bangitiy bang...] [810 The Over-Correction]

- The new Ted-designed GNB building is offically opened. [812 The Final Page Part 2]

- Barney proposes to Robin and she accepts. [812 The Final Page Part 2]

- Robin tells the gang she'd like to have her wedding in Canada, much to their amusement. [912 The Rehearsal Dinner].