Charlie starts to question his relationship with Chelsea when he hears that Mia is back in town. Meanwhile, Judith goes into labor and Charlie, Alan and Herb rush her to the hospital.

Alan and Chelsea become best buds, and Charlie decides to take advantage of the situation.

Charlie reluctantly agrees to let Chelsea move in as he mourns the loss of his bachelor pad. Meanwhile, Alan finds that there's not much space left for him in the house.

Chelsea sets Alan up on a blind date with her new friend. Rose.

Evelyn finally meets Chelsea and Charlie, and tries to prevent them from becoming friends.

Charlie joins Alan, Herb and his next door neighbor in a night of alcohol-fueled sexual reminiscences after Chelsea finds nude pictures of another woman on his phone.

When Chelsea gets sick and Charlie has to take care of her, he must also fight the overwhelming urge to flee.

Charlie tells Chelsea that he loves her, but doesn't get the response he expects.

Charlie has to remove a half-naked woman from his bedroom before Chelsea arrives.

Charlie finds himself in couples counseling.

Convinced that Alan's family doesn't fully appreciate him, Melissa invites Alan to live with her and her mom.

Judith is pregnant with a baby girl and Alan is convinced that he is the father. Meanwhile, Jake is in a contentious mood and Charlie thinks he knows why.

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

One of Charlie's old partners in crime dies, leaving Charlie to reevaluate his own reckless lifestyle.

Evelyn offers to pay for Jake's college education, leaving Alan to wonder if he ever needs to work again.

Jake disappears with the daughter of Charlie's neighbor, a former NFL player, and Charlie is left to cover his back. Meanwhile, Alan scores a hot date with the help of Charlie's Mercedes.

Charlie's new girlfriend asks him to spend the night at her place, while Alan tries to enforce a punishment on Jake.

Alan tries to escape Judith's grasp as Charlie and Herb go on the prowl.

When Judith kicks Herb to the curb, Alan comes knocking.

The guys bump into Jake's former teacher who became a stripper after a fling with Charlie. Charlie tries to help her out by giving her a room and a job, but things spiral out of control.

Charlie romances Alan's sweet receptionist as Alan anxiously awaits disaster.

Charlie tries cooking, Alan tries dating two women at the same time and Jake tries beer.

Alan lends Charlie money and crosses a line in his attempts to get it back.

Charlie encounters an ex whose son looks an awful lot like him.