Teens PJ and Teddy and tween brother Gabe are typical kids -- that is, until their mother has another baby. The arrival of their new sister completely upends the entire household. When their mother heads back to work after Charlie's birth, it's up to the kids and their dad to keep the home fires burning -- and to keep Charlie out of trouble as she learns to sit up, crawl, walk and run. Teddy, as the older sister, makes a personalized video diary for Charlie, in each episode adding a nugget of wisdom for her baby sibling.
Starting from where the season 3 finale left off, the Duncans' house has been destroyed by termites and they must build a new one, with the help of The Muppets.
Teddy moves on and looks for a new guy who looks just like Spencer.
Gabe has a crush on Mrs. Dabney's granddaughter.
After learning the big cheer competition will be held in Hawaii, Teddy decides to join Kelsey on the cheerleading squad; Teddy bombs her cheer tryout and has to beg the coach to give her another chance; Amy asks Gabe and PJ to take Toby to park.
Teddy struggles with applications for college and she dreams that she is in different times in the past. Gabe faces his old teacher. Bob gets an old rock look.
Teddy suspects that someone at school is out to get her. Amy and Bob suspect that Deedee Dooley is teaching Charlie bad behavior Gabe tries to prevent his report card from being mailed home.
Teddy throws a sleepover at PJ's apartment to forget about her anniversary with Spencer, while PJ and Emmett take care of their neighbor's pet rats while he's away. After Verne quits working for Bob to start his extermination business, Bob hires a young man named Beau (Luke Benward), as a replacement. Amy and Ms. Dabney use Gabe and Lauren to trick each other to do their chores but tables turn when Gabe and Lauren find out.
Amy goes all out for Charlie’s birthday.Teddy goes to work at Bob’s extermination business. Gabe is sent home from school for accidentally getting in a fight.
Ten years in the future, 14 year-old Charlie watches a video diary that Teddy made about a fight she had with Gabe, in hopes that it will guide her through her fight with an 11 year-old Toby.
Beau and Teddy and Bob and Amy go on dinner dinner dates, while PJ is in charge of Gabe, Charlie, and Toby.
An unexpected visitor creates drama for Teddy on her 18th birthday.
Bob and Amy attend the pest controllers annual dinner dance. Beau asks Teddy to the same event. Gabe scores tickets to the first showing of a hot new movie for an upcoming date.
Ivy tricks Teddy into joining her family trip to Las Vegas. Gabe is secretly playing league baseball because he doesn't want his mother to embarrass him. Bert and Mrs. Dobbs announce their marriage and want to have the wedding at the Duncan house.
Teddy and her friends go Halloween caroling to raise money for the drama club. A neighborhood mom vows to get even with PJ and Gabe for not giving her son any trick-or-treat candy.
After Teddy uncovers the reason why Amy and her younger sister Jamie drifted apart, she and Charlie quickly devise a plan to convince Amy that it's time to make things right with her sister. Meanwhile, Gabe and Jake sell a photo of Toby and are in hot water when a local grocery store winds up using it.
Beau gets a job offer and must decide whether to stay in Denver with Teddy or move back to Tennessee.
When Teddy gets accepted into a college in New York City, she goes to New York, alongside P.J. P.J stays at a hot dog cart and gets back together with Skyler. Meanwhile Teddy misses her tour on the subway and meets up with Jessie and Zuri. When a blizzard traps Teddy and P.J in New York City, they decide to stay with Jessie and Zuri.
Teddy is disappointed when she is waitlisted at her first choice for college.
Gabe discovers PJ has been living in the tree house in the backyard.
Teddy leaves for college and the family has a hard time saying goodbye.