Of Mice and Men is written in the form of a novella, which is fictional and shorter than a novel but longer than a short story. Steinbeck said that he decided to write the story in a similar way to a play, with a focus on using dialogue, and less description than is usual for prose fiction.
The play style is also evident in the structure as the book has three sections, like acts - each a pair of chapters; like scenes. Each chapter starts with an overview of the setting of that ‘scene’, similar to stage directions in a play.
The book has a third person narrator, but there is less narration than in traditional prose fiction and the action often moves on through the characters’ dialogue. Although the narrator is omniscient, they do not give a lot of insight into the characters’ thoughts and feelings, as some omniscient third person narrators do. Instead, this is suggested to the reader through the characters’ actions and what they say. This makes the style of writing quite direct and unemotional, which reflects the way that the characters live and relate to each other.