Zachary Gordon as Greg Heffley

Robert Capron as Rowley Jefferson

Devon Bostick as Rodrick Heffley

Peyton List as Holly Hills

Steve Zahn as Frank Heffley

Rachael Harris as Susan Heffley

Grayson Russell as Fregley

Karan Brar as Chirag Gupta

Melissa Roxburgh as Heather Hills

Laine MacNeil as Patty Farrell

Connor Fielding as Manny Heffley

Owen Fielding as Manny Heffley

Philip Maurice Hayes as Stan Warren

Terence Kelly as Grandpa Heffley

Bronwen Smith as Isabella Wendell-Jefferson

Alf Humphreys as Mr. Jefferson

Elise Gatien as Madison

John Shaw as Mr. Draybick

Andrew McNee as Coach Malone

Tom Stevens as Lenwood Heath

Bryce Hodgson as Ben Segal

Christopher De-Schuster as Chris the Bass Player

Dalila Bela as Taylor Pringle

Frank C. Turner as Troop Master Barrett

Emily Holmes as Mrs. Hills

Jeff Kinney as Mr. Jonathon Hills

Amitai Marmorstein as Cranium Shaker Operator

Roan Curtis as Girl at Cranium Shaker #1

Sydney Wong as Girl at Cranium Shaker #2

Reese Alexander as Cop

Cameron Mitchell Jr. as Country Club Manager

Latonya Williams as Receptionist Amy

Nicole Fraissinet as Receptionist Julie

Doug Abrahams as Rodrick's Rescuer

Melody B. Choi as Snack Bar Girl

Wanda Ayala as High Diving Fan

Kyle Cassie as Country Club Waiter

Kevin Kruchkywich as Country Club Pool Guy

Amy Esterle as Country Club Waitress

Gerry Durand as Country Club Valet

Joshua J. Ballard as Spag Union Math Boy

Matt Mazur as Spag Union Tracking Device Boy

Jared Abrahamson as Tim Warren

Matteo Stefan as Biff Warren

Collin MacKechnie as Chip Warren

Sofia Bowers as Li'l Cutie

Dawn Chubai as Newscaster

Anne Openshaw as Mrs. Warren

Keith MacKechnie as Man in Kitchen

Simon Chin as Restaurant Owner

BJ Harrison as Dry Cleaner

Russell Roberts as Confederate Soldier

Paul Fisher as Spag Union Announcer

David Palacio as Spag Union Boy

Peter Brown as Popcorn Vendor (uncredited)

Zeeshan Goawala as Student (uncredited)

Mark Redsky as Cook on Phone (uncredited)

Trenton Rogers as Student (voice) (uncredited)

Cameron K. Smith as Union Rifleman (uncredited)

James O'Sullivan as Sunblock Guy (uncredited)

Ian Thompson as Bus Driver (uncredited)