The film was shot in Toronto, Canada.

Filming Locations:

Cady's House (Exterior)

In the Movie

Scene where Cady's parents prepare her for her first day of school, and later she gets into a fight with Janis Ian at the entrance during a party.

In Reality

North Shore High School (Exterior)

In the Movie

Scene where Cady arrives on her first day of school and soon finds herself with two outcasts, Janis Ian and Damian, in the field behind the school.

In Reality

North Shore High School (Hallway/Bathroom)

In the Movie

Scene where On the first day, Cady hides in the bathroom to eat her lunch, and later she walks down the hallway with Janis Ian and Damian, learning about the school.

In Reality

The scene was filmed at The former school on Shaw Street before its closure in 2000. The new building opened in 2013 after a $17 million renovation.

North Shore High School (Gymnasium)

In the Movie

Scene where Cady is pulled out of health class to talk to the principal, and then the principal addresses all the female students. Later, students attend the Spring Fling held in the gym.

In Reality

Old Orchard Shopping Center

In the Movie

Scene where Cady goes to the mall with the Plastics and sees Janis Ian working there.

In Reality

Regina's House (Exterior)

In the Movie

Scene where The Plastics go to Regina's house to hang out.

In Reality

Street Near Cady's House

In the Movie

Scene where Regina complains to her boyfriend about Cady on the way to a party. She learns the full extent of Cady's deception when she returns to her parked car.

In Reality

North Shore High School (Principal's Office)

In the Movie

Scene where Regina tells Principal Duvall about the "Burn Book," and he interrogates Cady and two other students about it.

In Reality

The scene was filmed at A former nursing home, demolished in 2009.

Math Competition

In the Movie

Scene where Cady competes in the state math championship, which she wins in a sudden death round.

In Reality

The scene was filmed at Convocation Hall was designed by architects Darling and Pearson in the Edwardian Baroque style and opened in 1907 to host annual convocation ceremonies and other university events. The hall has a large domed rotunda seating about 1,700 people.