Dinnie, known by her full name "Domenica Santolina Doone", is the protagonist of the story. She is an American girl who is thrust into a cultured, diverse environment when she attends the international school her uncle is headmaster of it in Switzerland. She is kind and friendly, though shy. With the help of her new friends, Dinnie discovers who she is, and by the end of the book has more confidence in herself and in the world.
Peter Lombardy Guthrie the Third is a boisterous student who Dinnie befriends at the international school. This character lies next to the heart of Creech's novel - to preach the Bloomabilities (possibilities) and to celebrate each moment of life. Guthrie often shouts, "Sono Libero" (I am free), and Dinnie finally understands it was in the celebration of being alive. Guthrie is an optimistic fellow, seeing the good in everything. He also recites in the novel Robert Frost's well-known poem, "The Road Not Taken" in a speech to the student body as the school year closes.
Lila King is another American that Dinnie meets at the school. Though she is often pompous, hardheaded, somewhat prejudiced against non-Americans, Lila can be agreeable and quite friendly. Despite Lila's unfavorable qualities, Dinnie feels the need to stick by her as a friend and defend her. Lila has problems in her family, which maybe explains her often unacceptable personality. Guthrie refers to Lila as "the pistol".
Dinnie's aunt and sister of Dinnie's mother, a loving and supportive woman who humours Dinnie's wish to return to the United States. Aunt Sandy is also a teacher at the school that Dinnie attends. She and her husband Max provide Dinnie with a stable environment, which Dinnie has been lacking throughout her life.
The husband of Aunt Sandy, he is the headmaster of Dinnie's school, located in Lugano, Switzerland. As with Sandy, he is kindhearted and cares a great deal with Dinnie's well-being, helping her to adjust to her life abroad. Because of Max's position at the school, Dinnie is able to attend the school without paying the full tuition that other students must provide.
The glamorous and elegant founder of the international school that Dinnie attends. Though Max is the headmaster, Mrs. Stirling is the director of the school and highly respected by everyone. Despite her advanced age, she is extremely astute and aware of everything that is going at the school and fluent in English, French, and Italian.
A boy who came from Osaka, Japan and Guthrie's best friend. Because English is not his first language, he often pronounces words differently (like stupid as "stew pod") and coins new words to define existing concepts (bloomability for "possibility"), which are picked up by his friends. He is good-humoured and bright, and has a relationship with Belen Martinez, his classmate.
A girl who was a roommate with Lila, and is from Barcelona, Spain. She and Keisuke are in a relationship of sorts, though Belen is aware that her parents would not entirely approve of her dating a Japanese boy. She is a mature girl who comes across as somewhat moody and has strong opinions. However, she is not confrontational like Lila.
An Italian girl from Rome, Italy who joins Dinnie and her friends later in the novel, after the school's annual ski trip. She is friendly and cheerful, though a little hot-tempered.
Dinnie's family consists of her father Jack, her mother, her older brother Crick and her older sister Stella. Jack, who was born in Bybanks, Kentucky like Dinnie was, is constantly on the move with another job. He does not get along with his wife's family, whom he believes looks down on him for his country roots. Dinnie's mother was originally from New York and is a trained artist; though she prefers living in the city, she willingly travels around the United States in the wake of her husband's jobs. While Dinnie is in Switzerland, her mother infrequently responds to Dinnie's letters with slightly bizarre cards she has painted herself. Her mother, Dinnie's Grandma Fiorelli, originally comes from Campobasso, Italy, and disapproves of Jack's life style. Dinnie's brother Crick, due to being constantly on the move, frequently falls into delinquent behavior until, shortly before Dinnie is sent to Switzerland with Sandy and Max, is forcibly enlisted into the army in order to clean up his act. In contrast, Dinnie's sixteen year old sister Stella secretly gets married to a marine named George and has a baby, Michael, before Dinnie leaves for Switzerland. Throughout the novel, Dinnie receives news about her family from her paternal aunts, Tillie and Grace, who reside in Bybanks and often argue with one another. The sisters, however, express great love for their niece in their letters to Dinnie and offer encouraging news.