Lily begins acting out against the idea of having another baby in the house and frightens Mitchell and Cameron, who were planning on telling the family their good news. Meanwhile, both Claire and Jay find themselves desperate to prove they're right.
Claire recruits her family to help gather signatures for a petition to get a stop sign, Gloria loses the family dog, Jay helps Manny try to sell wrapping paper for school, and Cameron leaves a mess in the kitchen for Mitchell.
While Phil takes Haley on a tour of his Alma mater, Claire goes out on the town with a man she mistakenly assumes is Mitchell and Cameron's gay friend. Meanwhile, Gloria is alarmed and curious about Manny's mail-order package.
Phil tries to build a tree house, Haley struggles with writing a college admissions essay, Cameron hits on a single woman to win a bet with Mitchell, and Jay doesn't want to go out salsa dancing with Gloria and another couple.
As the family collects goods for a family whose house burned down, Jay makes an embarrassing remark to Phil during a massage, Claire is jealous of Mitchell's friendship with Gloria, and Cameron struggles with a moving van in a parking lot.
Phil is upset that Claire is stifling his creativity, Mitchell doesn't believe Cameron's "punkin chunkin" story, Gloria won't let Jay tell Manny that his Thanksgiving centerpiece is horrible, and Claire and Alex get in an accident.
After having a doctor's visit but then missing the call with the test results, Phil automatically jumps to conclusions and starts saying his goodbyes. Meanwhile Javier pops up unannounced again and takes Manny to the horse races for a belated birthday celebration, and a subtle competition ensues when Mitchell brings home an environmental law award and it becomes a game of who has the bigger trophy.
While Jay and Claire become hyper-competitive while working on their boys' science project, Gloria tries to help Phil with his real estate seminar. Meanwhile, Cameron and Mitchell interview a potential birth mother.
The family helps Claire prepare for her upcoming televised debate with Duane Bailey for the town council seat, but will they do more harm than good? Lily is going to be a precious flower girl for the first time, but the problem is she’s just discovered her first expletive and Mitch and Cam don’t know how best to deal with this new parenting test. And Jay is very concerned with Stella’s recent strange behavior and puts the blame on Gloria.
Phil is so preoccupied with impressing his new business partner, Tad (Greg Kinnear), that he doesn't notice what Claire believes is Tad being overtly inappropriate with her. Meanwhile, Jay and Gloria let Mitchell and Cameron stay over while their house is fumigated, and it turns out four is a crowd.
It's a day of disturbing realizations when Mitchell manages to ruin one of Jay's proudest golf moments, Phil overhears something that may forever change how he sees his little girl, and Gloria stumbles upon Claire's dangerous little secret. Luke and Manny try to get Lily into trouble because she is too cute .
Claire tries to help Luke cope with the death of their neighbor, Walt; Phil and Alex spend some time together; Haley throws a pool party without permission at Jay and Gloria's house; Cameron's father visits.
Gloria and Jay bicker while trying to order lunch at a diner; Claire and Cam have different theories on how to discipline kids; Luke accepts an award under false pretenses; Phil has a hard time firing Mitchell from his temporary job at the real estate agency; the entire family participates in Alex's living art display of Norman Rockwell's Thanksgiving painting, entitled "Freedom from want".