January 2011 ​

- Lily and Marshall find Barney's doppelganger, their fertility doctor Dr Strangel. [613 Bad News]​

- Marshall's father, Marvin, dies of a heart attack. [613 Bad News]​

- The gang go to St Cloud, Minnesota to attend the funeral of Marshall's dad, Barney decides to meet his dad. [614 Last Words]​

February 2011​

- Zoey sets Ted up with her hot cousin who the gang call "Honey". [615 Oh Honey]​

- After finding out Zoe is separated from her husband Ted and Zoey begin dating. [615 Oh Honey]​

- 13th. Barney meets Nora, Marshall returns to New York after spending the last month "taking care of his mother" in Minnesota. [616 Desperation Day]​

- 14th. Barney goes on his first date with Nora, playing laser tag. [616 Desperation Day]​

​- Barney and Nora go on their second date, Barney lies to Nora about wanting to settle down (even though this is actually what he wanted) and she slaps him and leaves, Robin dates a guy that acts like a dog. [618 A Change Of Heart]​

March 2011

- Barney reunites with his dad, Jerome Whittaker. [619 Legendaddy]​
April 2011 ​

– Lily’s 33rd birthday by which point Ted cannot remember the name of the girl he brought to her birthday last year (Amanda), Barney finally takes a bad photograph, much to the enjoyment of Robin. [518 Say Cheese]​

- Marshall quits his job at GNB to go work for the NRDC. [620 The Exploding Meatball Sub]​

- Barney and his dad go clubbing. [621 Hopeless]​

May 2011​

- Marshall joins Zoey in her efforts to save The Arcadian. [622 The Perfect Cocktail]​

- The Landmarks Preservation Committee meets to decide if The Arcadian is a landmark, and therefore couldn't been demolished to make way for Ted's new GNB building. Ultimately they decide it is not a landmark. As a result of the decision Ted and Zoey break-up. [623 Landmarks]​

June 2011

- A few weeks after breaking up with Zoe Ted starts dating his ex-girlfriend, (Boats! Boats! Boats!) Becky, again. [A few weeks after Ted and Zoey break up. 817 The Ashtray]

- Ted (who recently shared a sandwich with Becky), a drunk Robin and Lily attend an art gallery opening where they encounter Zoey's ex-husband, The Captain. Lily comments that she likes a piece of artwork depicting an elephant better than the one The Captain has above his bed and he tells her it doens't matter what she thinks because she's "just a kindergarten teacher". This really upsets her, and due to Aldrin Justice, she steals The Captain's expensive ashtray. What she doesn't realise is that The Captain later goes and buys the elephant piece. [817 The Ashtray]

​August 2011​

- 27th. During Hurricane Irene despite Teds best efforts to get the gang to go to the safety of his house outside of the city they end up staying in the city in Barneys apartment. While there Marshall pours Lily a bath and the two end up conceiving their child in Barney's bathtub. [This was a real life event and the speech by New York Mayor, Michael Bloomberg, in the episode occured on 27th August 2011. 709 Disaster Averted]​

- The next day. The gang play in the rain after the end of the storm and Marshall accidentally crashes a boogie board through the window of MacLaren's. As a result of this MacLaren's puts up a sign outside saying "No Boogie Boarding', Barney and Robin nearly kiss when Robins dad calls her. [709 Disaster Averted]​

September 2011

- The Arcadian is demolished to make way for the new Ted-designed GNB building. [624 Challenge Accepted]​

- After not seeing her for months Barney asks Nora out for coffee. [624 Challenge Accepted]​

- Lily finds out she is pregnant and quits smoking for good. [624 Challenge Accepted, it's revealed in 511 Last Cigarette Ever she quit when finding out she's pregnant.]​

- Ted appears in an article for New York magazine about him being the cities youngest ever architect with his design of the GNB building. [Came out shortly before 701 The Best Man]​

- Punchy's wedding, the gang finds out Lily's pregant, Marshall inadvertently reveals Punchy's bride, Kelly is also pregnant. [701 The Best Man]​

- Marshall starts a job as an environmental lawyer at Honeywell & Cootes. [702 The Naked Truth]​

- While attending the architects ball Ted runs in to ex-girl

friend Victoria. [703 Ducky Tie]​

- Victoria gets engaged to Klaus. [In 703 Ducky Tie he hadn't yet proposed to her but he clearly did propose as they schedule a wedding for May 2012]

- The next day. Barney loses a bet with Marshall and Lily and has to wear the ducky tie for a year. [703 Ducky Tie]​

October 2011​

- After assaulting a woman Robin is sentenced to therapy, where she meets Kevin [704 The Stinson Missile Crisis], Soon after Kevin says he cannot see her anymore as he liked her but couldn't ethically date her as her therapist.  For a week they have breakfast together every morning before deciding to just go on a date. [705 Field Trip]​

- Barney and Nora start dating. [704 The Stinson Missile Crisis]​

- Ted takes his class on a field trip but it doesn't go well when he finds he can't enter the GNB building site like he intended. [705 Field Trip]​

- Lily and Marshall find out they're having a boy. [706 Mystery vs. History]​

- Barney and Nora sleep together for the first time. [707 Noretta]​

- Shortly before Ted meets Naomi (aka the Slutty Pumpkin). Barney finds out he is 1/4 Canadian from Robin. [708 The Slutty Pumpkin Returns] 

- Before 31st. After searching for ten years Ted finally finds the Slutty Pumpkin, Naomi and they start dating even though they both find their relationship awkward but don't tell each other the truth and pretend everything is okay, Marshall and Lily are given a house in Long Island by Lily's grandparents who are moving to Florida. [708 The Slutty Pumpkin Returns]​

- 31st. Halloween. Ted and Naomi attend a Halloween party in the same outfits they did ten years ago. They confess to each other they find their relationship awkward and break-up. [708 The Slutty Pumpkin Returns]​

November 2011

- Marshall agrees to let Barney take off the ducky tie in exchange for getting three extra slaps to add to his one remaining slap outstanding from their 2006 slap bet. He agrees and Marshall gives out two of his four slaps immediately. [709 Disaster Averted]​

- Barney and Robin reminisce about the time they nearly kissed in August, after Hurricane Irene, but were interrupted. They make fun about what could have happened and end up kissing, and then sleeping together. [709 Disaster Averted]​

- Marshall, Ted and Lily go to Groova Palooza and Ted and Marshall get high. [710 Tick Tick Tick]​

- Barney and Robin decide to confess to their partners about their cheating and then meet at midnight to talk about their relationship. Barney tells Nora and they break up but when Kevin tells Robin he loves her, for the first time, she decides not to tell him. Barney is dejected when Robin shows up at MaClaren's, still with Kevin and leaves. [710 Tick Tick Tick]​

- Around 24th. The gang prepare for Thanksgiving at Lily and Marshall's house on Long Island. Lily and Marshall decide to move to the house on Long Island permanently, Robin tells Barney she thinks she's pregnant. [711 The Rebound Girl]​

December 2011

- Robin finds out that she not pregnant and, despite not wanting kids, she's upset to find out that she's infertile.  However she decides not to tell her friends the real reason why she's upset and tells them she can never be a pole vaulter instead. Ted does his best to cheer Robin up anyway. [713 Symphony of Illumination]​

- 31st. New Years Eve. At Marshall's insistence Lily rings and tells her dad she's pregnant. He barely acknowledges this news and hangs up, After having difficulty getting into MacLaren's Barney and Ted open up a bar in Ted's apartment, called Puzzles, Robin who is spending New Years Eve with Kevin gets a call from Sandy Rivers to come be his producer for the New Years Eve show. When Sandy gets drunk and leaves Robin has to take over as anchor. [714 Tailgate]

Sometime in 2011

- The night before taking her kindergarten class on a field trip to the jackhammer and siren museum Lily gets really drunk and is very hungover the following day. To help her Barney gives her some of his Stinson Hangover Fixir Elixir to help her feel better. [918 Rally].

​