Saoirse Ronan
Lady Bird McPherson

Laurie Metcalf
Marion McPherson

Tracy Letts
Larry McPherson

Lucas Hedges
Danny O'Neill

Timothée Chalamet
Kyle Sheible

Beanie Feldstein
Julie Steffans

Lois Smith
Sister Sarah Joan

Stephen McKinley Henderson
Father Leviatch

Odeya Rush
Jenna Walton

Jordan Rodrigues
Miguel McPherson

Marielle Scott
Shelly Yuhan

John Karna
Greg Anrue

Jake McDorman
Mr. Bruno

Bayne Gibby
Casey Kelly

Laura Marano
Diana Greenway

Marietta DePrima
Miss Patty

Daniel Zovatto
Jonah Ruiz

Kristen Cloke
Ms. Steffans

Andy Buckley
Uncle Matthew

Kathryn Newton
Darlene Bell

Myra Turley
Sister Gina

Bob Stephenson
Father Walter

Abhimanyu Katyal
Friendly Banker

Chris Witaske
Business Jock

Ben Konigsberg
David From College

Richard Jin Namkung
Cool Coffee Manager

Robert Figueroa
Cast Removal Doctor

Carla Valentine
Guidance Counselor

Roman Arabia
Luis Cruz

Monique Edwards
NYC Nurse

Matthew Maher
NYC Man on Street

Anita Kalathara
Prom Chairwoman

Georgia Leva
Senior Class Candidate

London Thor
"Merrily We Roll Along" Performer

Shaelan O'Connor
"Merrily We Roll Along" Performer

Christina Offley
"Merrily We Roll Along" Performer

Sabrina Schloss
"Merrily We Roll Along" Performer

Connor Mickiewicz
"Merrily We Roll Along" Performer

Ithamar Enriquez
Driving Instructor

Danielle Macdonald
Another Young Lady

Rebecca Light
Mr. Bruno's Wife

Janet Song
Administrator (uncredited)