India Opal Buloni is the 10-year-old daughter of a preacher, and has recently moved into a Florida trailer park with her father, after her mother left them. While in a Winn-Dixie supermarket, she finds a stray dog, and not wanting him to be sent to the pound, claims he is hers, and that his name is "Winn-Dixie".
A musical is being made of the story, starring a highly-trained dog as Winn-Dixie.
The book and film provide examples of:
- Academic Athlete: Opal enjoys hearing stories from others, and judging by her respect for the library and librarian, it can be inferred she likes to read.
- Alpha Bitch: Amanda shows shades of this, though it's very downplayed. She's not really one; her perceived sour attitude is implied to be a result of her brother's death.
- Amplified Animal Aptitude: Winn-Dixie appears to be able to understand Opal's emotions, and also appears to be able to smile like a human.
- A Boy and His X: A girl and her dog. The focus of the story is about Opal's growing relationship with Winn-Dixie and how he affects her, such as helping her heal from her mother's abandonment.
- By-the-Book Cop: The film has one of these, a sheriff who appears to enjoy harassing pet shop owner Otis, scolding kids for doing absolutely nothing, and in general, being a real pain. His by-the-book side comes from the fact that every time anyone crosses him, he starts shouting the ordinance they're in violation of. (Considering the violators are usually animals, it's not like they care).
- Broken Bird: Amanda, who lost her brother, Carson, in an accident, the loss of which she never quite recovered from, so she takes out her feeling because of it.
- Calling the Old Man Out: Opal does this to Preacher after she loses Winn-Dixie. She goes home expecting to find him, and when her dad tries to get her to come in out of the rain, she confronts him on not showing up for her party, and seeming to ignore her all the time.
- Child Hater: Mr. Alfred, who's also a dog-hater, as evidenced by his rule against both kids and pets in his trailer park. This nearly gets Winn-Dixie sent to the dog pound. He comes around in both the girl and the dog's cases by the end.
- Church of Saint Genericus: The Preacher's church has no specific denomination, and services are held in a repurposed convenience store, still known as the Pick-It-Quick. In the movie it's a Baptist church according to the sign on the door.
- Colour-Coded Characters: Among the three main girl characters, Amanda tends to wear blue, Opal red and Sweetie-Pie pink.
- Everyone Calls Him "Barkeep": Everyone in town calls Opal's dad "Preacher." She does too, though not to his face.
- Evil-Detecting Dog: Inverted. Winn-Dixie actually leads Opal to potential friends rather than detecting evil, though he does do his share of barking at Mr. Alfred and the Dewberry brothers before they too become friends.
- Fear of Thunder: The dog is horribly afraid of thunderstorms (truth in television).
- Free-Range Children: Opal and the other kids seem to run around town without much adult supervision. May be justified in that Naomi is a very small town.
- Insubstantial Ingredients: Miss Franny tells the girls that the Littmus Lozenge's secret ingredient is sorrow.
- Line-of-Sight Name: Opal christens her dog Winn-Dixie since she found him in a grocery store and claimed him on the spur of the moment.
- Missing Mom: Opal's mom left when she was three. Opal doesn't know why, but her dad eventually reveals that she was an alcoholic and hated being a preacher's wife.
- Old Maid: The librarian, Miss Franny Bloch, though she subverts this trope, explaining to Opal that she never had the need to be married.
- Only Known by Their Nickname: Sweetie Pie Thomas is only ever called "Sweetie Pie" and we never hear her real name.
- Plucky Girl: Opal plays baseball and was her former hometown's star pitcher. She's also a pretty gutsy kid in general, as seen by her willingness to befriend town "witch" Gloria Dump, stand up to the Dewberry brothers, and ride her bike just about anywhere in the neighborhood.
- Pounds Are Animal Prisons: Invoked. Twice, Opal goes to somewhat great lengths to save Winn-Dixie from the dog pound.
- Puppy Love: It's heavily implied that the nicer of the Dewberry brothers has a crush on Opal. Opal herself doesn't really reciprocate or even seem to notice, at least not until the end where she smiles at him kindly as they share a moment when they think Winn-Dixie's gone for good.
- In the musical, Sweetie Pie has a clear crush on Stevie, though he clearly doesn't reciprocate.
- Title Drop: "Just about everything that happened to me that summer happened because of Winn-Dixie."
- Tomboy and Girly Girl: There are hints of this between Opal, the tomboy, and Amanda, who generally wears skirts and elaborately styles her hair, and is never seen playing sports.
- Trademark Favorite Food: Winn-Dixie loves peanut butter. In the film, at least, he gorges himself on Miss Franny's Littmus Lozenges.
- War Is Hell: Invoked; Miss Franny quotes it word for word while telling Opal and Amanda about her great-grandfather Littmus, who fought in the Civil War.