Every Fireside Girl has participated in several of Phineas and Ferb's Big Ideas, with Isabella being the most common.
Participation in the Big Ideas[]
| Episode | Participation | Participating Fireside Girls |
| "Rollercoaster" | Watched the unveiling of Phineas and Ferb's Rollercoaster. | Katie and Ginger |
| "Lawn Gnome Beach Party of Terror" | Helped as lifeguards at the backyard beach. | All of them |
| "Flop Starz" | Sung in the band Phineas and the Ferb-Tones, in a group called The Ferbettes (a spoof of Alvin and the Chipmunks's The Chipettes) | Gretchen, Adyson and Milly |
| "The Fast and the Phineas" | Acted as Phineas's pit crew. | All of them |
| "Lights, Candace, Action!" | Helped on the movie set. | Gretchen, Holly, Milly, Adyson and Ginger |
| "Raging Bully" | Helped the ring's construction and gave out fliers of the brawl. | All of them |
| "Candace Loses Her Head" | Distracted Candace from seeing her present. | All of Them |
| "Run Away Runway" | Helped create the Summer All The Time Collection. | Holly, Milly, Ginger, Adyson and Katie |
| "S'Winter" | Helped to create and sang S'Winter. | All of them |
| "Jerk De Soleil" | Participated in the show as acrobatic performers. | All of them, plus other unofficial Fireside Girls |
| "Get That Bigfoot Outa My Face!" | Went to Camp Phineas and Ferb to earn various accomplishment patches. | All of them |
| "Mom's Birthday" | Helped with the festivities and sang background vocals on I Love You Mom. | All of them |
| "It's About Time!" | Built a new time machine to rescue Candace and the boys from prehistoric times. | All of them |
| "Dude, We're Getting the Band Back Together" | Built the stage for Love Händel's performance and became backup dancers. | All of them |
| "Tree to Get Ready" | Witnessed the tree house fight. | All of them |
| "The Ballad of Badbeard" | Assisted in the search for Badbeard's Treasure on Spleen Island. | Gretchen, Holly, Milly, Ginger and Adyson |
| "Greece Lightning" | Rode in the chariot race. | Holly and Katie |
| "Leave the Busting to Us!" | Went on the Ferris wheel and water slide. | Holly and Ginger |
| "Comet Kermillian" | Watched the comet in the observatory. | Holly only |
| "Put That Putter Away" | Built and played on Phineas and Ferb's mini-golf course, and dancers during the Disco Miniature Golfing Queen song. | Ginger, Adyson, Holly and Gretchen |
| "The Flying Fishmonger" | Helped sing the original song and the new, improved song. | Gretchen, Holly, Milly, Adyson and Katie |
| "One Good Scare Ought to Do It!" | Constructed the Haunted House and dressed up in monster costumes to scare away Isabella's hiccups. Also saved Phineas's life when he fell. | All of them |
| "Out of Toon" | Helped on the making of the giant TV and the Phineas and Ferb Studios. | Milly, Ginger, Adyson and Katie |
| "Out to Launch" | Worked in the space port to monitor the boys' launch. | All of them |
| "Interview With a Platypus" | Helped by interviewing the talking animals. | Milly, Ginger, and Adyson |
| "Tip of the Day" | Helped spread the awareness of aglets and sung in the Aglet-Aid concert. | All of them |
| "Day of the Living Gelatin" | Helped Phineas and Ferb mix the ingredients for the giant gelatin and later defeated it. | All of them |
| "Don't Even Blink" | Helped on finding where the projects Phineas and Ferb's creations disappear to. | All of them |
| "Chez Platypus" | Cooked and served delicious foods at Chez Platypus. | All of them |
| "Thaddeus and Thor" | Witnessed and the unveiling of the fort. | All of them |
| "De Plane! De Plane!" | They helped Phineas and Ferb break the world record for biggest airplane in the world and appear as backup singers for "Big Ginormous Airplane". | All of them |
| "Let's Take a Quiz | They helped Phineas and Ferb organize their show to earn their patches. | Gretchen, Holly and Ginger |
| "At the Car Wash" | Ran the car wash so they can save the Starnose Mole. | All of them |
| "Oh, There You Are, Perry" | Helped sing Come Home, Perry. | All of them |
| "That Sinking Feeling" | Rode along in the ocean cruise ship. | Gretchen, Ginger, Adyson, and Holly |
| "Spa Day" | Helped the boys in the Spa. | Gretchen, Holly, Milly, Ginger, and Katie |
| "Bubble Boys" | Went in the bubble with Phineas and the boys. | All of them |
| "Isabella and the Temple of Sap" | Went to retrieve the sap from the Maracanut Tree for Phineas. | All of them |
| "Cheer Up Candace" | Attended Phineas and Ferb's Comedy Club. | Holly, Ginger and Milly |
| "Fireside Girl Jamboree" | Helped Candace become a member of the Fireside Girls. | All of them, and Candace |
| "What Do It Do?" | Helped Phineas and Ferb find out what the robot does. | Katie and Holly |
| "Phineas and Ferb Christmas Vacation!" | Danced during the Ending Credits. | Katie, Holly, Milly, Ginger and Adyson |
| "Candace's Big Day" | Helped the boys with Tiana and Bob's wedding. | All of them |
| "I Was a Middle Aged Robot" | Helped Cheer for Lawrence and Candace. | All of them, plus two new Fireside Girls: |
| "Hip Hip Parade" | Went along in the Parade. | Ginger and Holly |
| "Robot Rodeo" | Acted as Rodeo Clowns in the Rodeo. | Adyson, Gretchen, and Holly |
| "The Beak" | Delivered the Fireside Girls Gazette in the neighborhood. | Unknown Fireside Girl (blond) only |
| "The Lemonade Stand" | Helped franchise and sells P&F Lemonade. | Ginger, Milly, Adyson, Gretchen, and Holly |
| "Wizard of Odd" | Acted as Patchkins and sings The Yellow Sidewalk | Gretchen, Unknown Fireside Girl (blond), Adyson, Holly, Ginger, Milly, and Katie, plus a new Fireside Girl: |