At 12 years old, Rosalind is the oldest Penderwick sister and acts as a proxy mother figure to her younger siblings. She takes her responsibilities seriously, overseeing Batty's bedtime routine and managing the daily chaos of family life. Her practical nature conflicts slightly with her budding adolescent feelings, particularly her new interest in the Arundel groundskeeper.

Skye is the fiery, pragmatic 11-year-old middle sister, distinguished by her blonde hair and blue eyes. She loves mathematics, logic puzzles, astrophysics, and soccer, preferring concrete facts over her sisters' imaginative games. Her sharp tongue occasionally causes trouble, but she passionately defends her family when they face criticism.

Ten-year-old Jane is a wildly imaginative author who constantly views the world as material for her Sabrina Starr adventure novels. She often confuses fantasy with reality, finding dramatic inspiration in the people she meets at Arundel. She plays center forward on her soccer team and maintains an optimistic, resilient view of others.

Four-year-old Batty is the shyest and youngest member of the family, rarely seen without her trusty butterfly wings. Having never known her mother, she relies heavily on Rosalind for comfort and guidance. She loves animals deeply and uses her quiet observation skills to connect with the pets she meets on the Arundel estate.

Jeffrey is the lonely 11-year-old son of the wealthy Mrs. Tifton. Raised by his mother and his late grandfather, he lives under the heavy weight of military expectations despite his natural talent for playing the piano. His solitary daily routine changes completely when he meets the neighboring Penderwick sisters.

Brenda Tifton is the pretentious and aristocratic owner of Arundel Hall. She obsesses over her manicured gardens, strict manners, social status, and the upcoming Garden Club competition. Having raised her son alone after a scandalous divorce, she rigidly enforces rules and plans to send Jeffrey to an elite military academy.

Mr. Penderwick is a gentle, knowledgeable botany professor raising four daughters as a single parent. He speaks Latin, deeply loves flowers, and maintains a relaxed, empathetic parenting style that encourages his children's creativity and independence.

Mrs. Tifton's pompous and snobbish boyfriend, who belongs to an exclusive country club and works as a magazine publisher. He supports sending Jeffrey to military school early so he can marry Mrs. Tifton and travel without the burden of a child.

The late mother of the Penderwick girls, who died of cancer shortly after Batty's birth. Her memory remains a strong, guiding presence in the family, especially for Rosalind, who shares bedtime stories about her with the youngest sister.

The Penderwicks' large, enthusiastic, and often clumsy family dog. He acts almost like a fifth child, possessing a knack for escaping his enclosure and fiercely protecting Batty when she needs comfort.

The young, handsome groundskeeper at Arundel Hall who lives in the carriage house. He loves Civil War history, keeps two pet rabbits, and works hard to maintain Mrs. Tifton's strict landscaping demands while indulging the visiting children.

The warm, kind-hearted housekeeper and cook at Arundel Hall. She acts as a surrogate mother to Jeffrey and enthusiastically welcomes the loud, chaotic energy of the Penderwick sisters by feeding them gingerbread and lending them dresses.

A friendly roadside tomato salesman who correctly predicts the trouble the Penderwick girls will cause. Having grown up with six sisters, he appreciates the girls' lively nature and warns them to avoid Mrs. Tifton's prized gardens.

Mrs. Tifton's late father and Jeffrey's grandfather. A proud military man whose imposing portrait hangs in the dining room, his legacy sets the strict expectations Mrs. Tifton forces upon her son.

An unpleasant boy from a wealthy family whom Mrs. Tifton considers a suitable companion for Jeffrey. Jeffrey avoids him, preferring the company of the Penderwick sisters.

A wealthy English judge for the Garden Club competition. His presence makes Mrs. Tifton highly anxious, as she desperately seeks his professional approval.

One of Cagney's two pet rabbits. His unexpected escape into the gardens causes a chaotic chase involving Batty, Hound, and Mrs. Tifton.

A red-haired girl who is Cagney's girlfriend, whose presence abruptly shatters Rosalind's romantic illusions about the groundskeeper.

Rosalind's best friend back home, whom she frequently writes to and relies on for advice regarding boys and conversation rules.