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)