Season 4, Episode 1: Do I Know You?

Original Air Date—22 September 2008

Ted and Stella get engaged, but Ted soon learns that he doesn't know anything about her. Meanwhile, Barney confesses to Lily that he's in love with Robin
	
Season 4, Episode 2: The Best Burger in New York

Original Air Date—29 September 2008

Marshall claims that he had the best hamburger in the world during his first week in New York City, but he forgot where the burger joint is located. The gang then hits the streets of Manhattan to help him find it.
	
Season 4, Episode 3: I Heart NJ

Original Air Date—6 October 2008

Ted does not want to move in with Stella because he hates New Jersey. Robin prematurely quits her TV job because she incorrectly thinks that she already has a new job.
	
Season 4, Episode 4: Intervention

Original Air Date—13 October 2008

Ted, Robin, Marshall, and Lily all begin getting cold feet because of their imminent life changes, and Barney tries to prove that he can pick up a woman while posing as an 80-year-old man.
	
Season 4, Episode 5: Shelter Island

Original Air Date—20 October 2008

Ted and Stella move up their wedding date, but the wedding may not go off as planned after Ted breaks the "No Exes Rule" and invites Robin to come in from Japan for the wedding.
	
Season 4, Episode 6: Happily Ever After

Original Air Date—3 November 2008

The gang tries to hide from Stella when they discover that they are eating at the same restaurant.
	
Season 4, Episode 7: Not a Father's Day

Original Air Date—10 November 2008

While Barney celebrates a pregnancy false alarm, Marshall and Lily try to figure out if it's time to have a baby.
	
Season 4, Episode 8: Woooo!

Original Air Date—17 November 2008

Lily is disappointed to discover that Robin is secretly a "Woooo! Girl," and Barney secretly sabotages Ted's chance to get the contract to design a new bank skyscraper.
	
Season 4, Episode 9: The Naked Man

Original Air Date—24 November 2008

When the gang learns that a bold, desperation date move got Robin into bed, Ted and Barney decide to try it out for themselves.
	
Season 4, Episode 10: The Fight

Original Air Date—8 December 2008

The guys get invited to fight alongside Doug the Bartender. However, the fight doesn't go exactly how they imagined it to.
	
Season 4, Episode 11: Little Minnesota

Original Air Date—15 December 2008

Ted tries to keep his irresponsible sister from hooking up with Barney during her trip to New York, and Robin starts hanging out with Marshall at a bar for Minnesotans, not telling them that she's really Canadian.
	
Season 4, Episode 12: Benefits

Original Air Date—12 January 2009

Ted and Robin discover that sex with each other solve their fights as roommates, which makes Barney very jealous and angry. Meanwhile, Marshall reveals that he's too embarrassed to use the office bathroom.
	
Season 4, Episode 13: Three Days of Snow

Original Air Date—19 January 2009

During a historic blizzard, Ted and Barney get an opportunity to run their own bar, while Marshall and Lily try to defy the odds and continue one of their cherished traditions.
	
Season 4, Episode 14: The Possimpible

Original Air Date—2 February 2009

Robin needs to find a television job in seven days or else she loses her work visa, and Barney volunteers to come to her aid. Meanwhile, Ted, Marshall, and Lily consider cleaning up their resumes
	
Season 4, Episode 15: The Stinsons

Original Air Date—2 March 2009

The guys find out that Barney is pretending to have a wife and son to make his mother happy, but the charade is blown when Ted makes a move on Barney's "wife."
	
Season 4, Episode 16: Sorry, Bro

Original Air Date—9 March 2009

Ted meets with his ex-girlfriend from college--a girlfriend who cheated on him constantly and Marshall and Lily can't stand, and Marshall tells the story about how he forgot to bring his pants to work.
	
Season 4, Episode 17: The Front Porch

Original Air Date—16 March 2009

Ted becomes angry with Lily when he finds out that she has been sabotaging all his relationships that she did not approve of, including his relationship with Robin.
	
Season 4, Episode 18: Old King Clancy

Original Air Date—23 March 2009

Barney and Marshall don't tell Ted that the plans for the building he has been working on have been scrapped, and the guys try to figure out which Canadian celebrity Robin slept with.
	
Season 4, Episode 19: Murtaugh

Original Air Date—30 March 2009

Barney tries to do all the items on Ted's "I'm to old for this stuff" list, while Marshall's over-competitive side comes out when he coaches Lily's Kindergarten basketball team.
	
Season 4, Episode 20: Mosbius Designs

Original Air Date—13 April 2009

Ted's plans to make his own design firm in his apartment hit a snag when his personal assistant begins sleeping with Robin, and Marshall tries to find a way to make himself indispensable at his workplace.
	
Season 4, Episode 21: The Three Days Rule

Original Air Date—27 April 2009

Ted gets around the three-day rule by texting a woman he just met, but he doesn't realize that he's actually texting Barney and Marshall.

Season 4, Episode 22: Right Place Right Time

Original Air Date—4 May 2009

Ted recounts the series of random events that lead up to the chance meeting with the woman who would eventually become his wife.
	
Season 4, Episode 23: As Fast as She Can

Original Air Date—11 May 2009

Stella's boyfriend Tony breaks up with her after having a conversation with Ted, prompting Stella to come back to Ted with a surprising request.
	
Season 4, Episode 24: The Leap

Original Air Date—18 May 2009

While Ted struggles with an unorthodox architecture project, Robin finds out that Barney is in love with her, and Marshall threatens to take a long-considered leap from the roof to a neighboring building.