For the first time The Chipmunks meet their female counterparts, The Chipettes: Brittany, Jeanette and Eleanor.

A charaltan chipmunk named Harry claims to be Alvin, Simon and Theodore's long lost uncle and says he will have them see their mother as soon as they make enough money. The Chipmunks later not only find out that Harry is not their uncle but also the money he has them making is for a carnival strongman who he has owed for a long time.

Dave has a nightmare of himself getting smaller and smaller.

Dave drags the Chipmunks unwillingly on a camping trip in the great out doors. When they finally arrive, the Chipmunks discover large footprints and think they are being followed by Bigfoot. Eventually they build a treehouse for Dave, when he falls and injures himself badly, and Alvin and Simon go in search for Big Foot.

Charlatan chipmunk Harry returns and this time pretends to be Santa Claus and cons Alvin, Simon and Theodore into building a Christmas-themed amusement park called ""Santa's Place"".

The chipettes move to the Chipmunks school and Alvin and Brittany run against each other for class president. Both will stop at nothing to win, but when the polls are revealed they discover that Jeanette has the deciding vote.

Alvin is determined in getting an invitation to participate the Celebrity Ski Tournament. Once he convinces Mr. Colorado, the man hosting the event, to let him participate, all Alvin has to do then is learn how to ski.

The Chipmunks and the Chipettes volunteer their talents to raise the money to keep the circus going.

The Chipmunks get the measles. Dave spends so much time taking care of his boys that he becomes sick with the measles and is not able to fix his car for the car show. It is up to the boys take care of everything for Dave.

Alvin's favorite hat goes missing.

Alvin gets a crush on his teacher.

Dave, the Chipmunks and the Chipettes go to Washington D.C. to lobby the president to save bald eagles.

Alvin sells Dave's motor home to buy a gold claim.