Saoirse Ronan
as Lady Bird McPherson

Laurie Metcalf
as Marion McPherson

Tracy Letts
as Larry McPherson

Lucas Hedges
as Danny O'Neill

Timothée Chalamet
as Kyle Sheible

Beanie Feldstein
as Julie Steffans

Lois Smith
as Sister Sarah Joan

Stephen McKinley Henderson
as Father Leviatch

Odeya Rush
as Jenna Walton

Jordan Rodrigues
as Miguel McPherson

Marielle Scott
as Shelly Yuhan

John Karna
as Greg Anrue

Jake McDorman
as Mr. Bruno

Bayne Gibby
as Casey Kelly

Laura Marano
as Diana Greenway

Marietta DePrima
as Miss Patty

Daniel Zovatto
as Jonah Ruiz

Kristen Cloke
as Ms. Steffans

Andy Buckley
as Uncle Matthew

Paul Keller
as Parish Priest

Kathryn Newton
as Darlene Bell

Myra Turley
as Sister Gina

Bob Stephenson
as Father Walter

Abhimanyu Katyal
as Friendly Banker

Chris Witaske
as Business Jock

Ben Konigsberg
as David From College

Gurpreet Gill
as Convenience Store Clerk

Richard Jin Namkung
as Cool Coffee Manager

Joan Patricia O'Neil
as Danny's Grandmother

Robert Figueroa
as Cast Removal Doctor

Carla Valentine
as Guidance Counselor

Roman Arabia
as Luis Cruz

Monique Edwards
as NYC Nurse

Matthew Maher
as NYC Man on Street

Anita Kalathara
as Prom Chairwoman

Debra Miller
as Saleswoman Joyce

Georgia Leva
as Senior Class Candidate

Derek Butler
as "Merrily We Roll Along" Performer

London Thor
as "Merrily We Roll Along" Performer

Shaelan O'Connor
as "Merrily We Roll Along" Performer

Christina Offley
as "Merrily We Roll Along" Performer

Sabrina Schloss
as "Merrily We Roll Along" Performer

Connor Mickiewicz
as "Merrily We Roll Along" Performer

Erik Daniells
as "Merrily We Roll Along" Performer

Cynthia Cales
as Immaculate Heart of Mary Teacher

Giselle Grams
as Immaculate Heart of Mary Teacher

Ithamar Enriquez
as Driving Instructor

Luisa Lee
as Young Lady

Danielle Macdonald
as Another Young Lady

Adam Brock
as Band Lead Singer

Bonnie Jean Shelton
as Fab 40s Realtor

Rebecca Light
as Mr. Bruno's Wife

Janet Song
as Administrator (uncredited)