Berta's daughter, Naomi is pregnant and Berta drags Charlie with her when she confronts the baby’s father. Alan reveals a secret fetish.

Alan suffers from insomnia. He visits his psychiatrist, who reveals that the cause of Alan's sleepless nights is his jealousy towards Charlie, and his inability to glide through life.

Charlie's friends and family put a crimp in his plan for a romantic Christmas Eve date. When Evelyn sees who the date is, she goes to great lengths to force a wedge between them.

Charlie sets Alan up with their new neighbour. But he gets jealous when the two form a bond.

After Evelyn tells Alan and Charlie how she feels about there being no mourners at her friend’s funeral, the boys share their feelings that this could also be the case at her funeral. Evelyn tries to prove them wrong by introducing them to a couple she help adopt a boy from China. The boys return fire by inviting the young man to a play date with Jake.

Alan looks forward to Judith's wedding, while Charlie and Myra continue their romance.

Jake gets lucky after Charlie takes him to the racetrack. Meanwhile, Alan has a difficult time at the DMV.

Charlie is shocked when the handyman working on his house beats him out for Chloe's affections. Alan has no sympathy for Charlie’s distress.

Charlie acts strange after spending an evening with his mother, and a woman Alan slept with behaves oddly the next morning.

Charlie and Linda get closer to consummating their relationship, but Charlie has trouble focusing when he begins to see Rose's face everywhere he turns.

Charlie's girlfriend is embrassed to go out in public with him. Meanwhile, Jake sneaks out to attend a concert.

When Alan finds himself wanting to break up with a woman, Charlie offers his expertise.

Charlie double-dates with Jake and fixes Alan up with a hooker.

Charlie's attracted to an older self-help author. Alan and Jake clash over a project for school.

In the 6th season opener, Charlie runs into an ex-girlfriend and a child who bears a striking resemblance to Charlie.

Alan is sure that things will turn bad when Charlie starts dating his receptionist.

When Judith kicks Herb to the curb, Alan comes knocking; Jake is sent to stay with a less-than-willing Charlie for three months during Judith's meltdown.

Charlie's new girlfriend Chelsea asks him to spend the night at her place, which puts Charlie well outside of his comfort zone, while Alan tries to enforce a punishment on Jake initiated by Judith for mooning a group of girls.

Charlie finds himself re-examining his wild ways when an old friend dies and begins to feel that his time on Earth may be drawing to a close.

Charlie and Jake fight for the affections of a waitress, while Alan fights sexual tension with his receptionist.

Judith is pregnant with a baby girl and Alan is convinced he is the father.

Melissa doesn't think Alan's family appreciates him, so she asks him to move in with her and her mom.

Charlie's admission that he's in love with Chelsea gets a surprising reaction from her

Chelsea's illness gives Charlie a chance to prove he can take care of her, but also yearning to run away from the situation.

After Chelsea discovers a nude picture of another woman on Charlie's cell phone, he blows off steam by going out for a night of drinking with Alan, Herb and his neighbor.

Charlie mourns the loss of his bachelor pad as he reluctantly allows Chelsea to move in. Meanwhile, Alan discovers there is no longer much space left in the house for him.

Jake stops at nothing to get away from Charlie and Alan, after they embarrass him out in public.

Charlie has a return engagement with Chelsea's best friend, while Alan has an unexpected effect on a new female patient.

Alan is torn between the bad influence of Jake's new friend and the hotness of his mother.

Charlie and Alan try to set up Evelyn with Russell the pharmacist.

Obsessed and believing her to be married, Charlie starts stalking Rose. Jake and Eldridge start taping themselves doing Jackass-style stunts.

While Charlie and Rose carry on their "affair," Alan's chiropractic business turns into a Ponzi scheme.

Alan and Jake meet Walden Schmidt, a broken-hearted billionaire.

Walden deals with his ex-wife, Bridget.

Walden goes looking for Mrs. Right while Alan has an opportunity to reconcile with Lyndsey.

Alan has trouble accepting Lyndsey's seedy movie past, and Walden tries to cheer him up by throwing a party.

Walden receives divorce papers from Bridget, but forgets his depression when he meets a girl who looks eerily like her.

Jake has a crush on his chemistry tutor, who has a crush on Walden. Meanwhile, Alan obsesses over the journal his brother left him in his will.

When Walden begins redecorating the beach house, Alan becomes overly emotional.

Walden hits it off with a British babe, but neither of them is sure he's ready to re-enter the dating world.

Walden is trying his best to impress his new love interest when Bridget reappears in his life.

Walden's mother arrives and Alan is smitten with her, even as she reveals a secret about Walden's past that sends him into a downward spiral.

Walden’s ex-wife and mother try to take control of his company, so he turns to Alan for help.

Zoey tries to convince Walden to cut his hair and shave; Alan and Lyndsey revive their relationship.

Walden tries to loosen Zooey up by sharing some of Berta's special brownies.

Strained relationships and girl-fighting result when a huge storm traps Walden, Alan, Zoey and Lyndsey in the house on Valentine's Day.

Walden and Zoey's relationship suffers after they share a near-death experience. Meanwhile, Alan wonders if Lyndsey has a drinking problem.

Walden's ex-business partner shows up at the beach house looking to make peace.

Alan and Lyndsey introduce their mothers. Jake and Eldridge get a ride from Walden to a party.

Walden breaks the news to Zoey that he is going into business with his ex-wife. Alan and Lyndsey try to cope with their mom's relationship.

Walden's commitment is tested when Zoey and her daughter come to live with him. Meanwhile, Alan gets more than he bargained for when he moves in with Lyndsey

Charlie's ghost pays a visit to Alan after he suffers a minor heart attack.

Alan is showered with love and affection upon returning from the hospital, but Zoey isn’t so sure it’s deserved.

Jake is pressured to make a decision about his future.

Walden plans a big surprise for Zoey's birthday.

Zoey and Walden break up, causing Walden to experience a breakdown.

Alan and Lyndsey decide to spice things up in the bedroom.

When Alan learns Walden knows Lynda Carter, he asks him to set him up on a date with her. Against his better judgment, Walden agrees to invite her to the house for dinner.

Walden goes on a date with an accident-prone model; Alan's date reveals surprising personal information about herself to him.

Lyndsey's boyfriend sets Alan up on a date; Walden wants to help Nicole with her project so she will have time to date him.

Walden thinks his girlfriend is cheating on him; Alan starts dating Larry's sister, Gretchen (Kimberly Williams-Paisley).

After reconnecting with Kate, Walden becomes convinced she is the one for him -- until he meets a woman named Vivian (Mila Kunis).

After a health scare on Halloween, Walden decides he needs to change his life.