Of Mice and Men’s tone is consistently solemn, and turns tragic as the conclusion nears. From the very beginning, this heaviness of tone creates a sense of impending, inescapable doom. For example, George and Lennie are first described as wearing “black, shapeless” clothing, and one of the first conversations they have is about the dead mouse in Lennie’s pocket. Even the idyllic, green setting in which the novella begins cannot overcome the sense of death that follows these characters. As the story continues, the grave nature of the characters’ daily lives becomes even more apparent: George receives a lice-infested bunk, Carlson shoots Candy’s old dog, Crooks lives in the isolated stable, Lennie accidentally kills a puppy. The depictions of the living conditions in which these poor workers find themselves contribute to the solemn tone throughout, and the tone turns tragic as these circumstances compel George to kill Lennie.

The intense seriousness of the novella’s tone occasionally tips over into sentimentality. For instance, Crooks’s eyes “glitter with intensity,” George falls “morosely silent,” and Curley’s wife is described after her death as having “the meanness and the plannings and the discontent and the ache for attention” leave her face. These descriptions appear melodramatic compared to the often crude and choppy dialogue of the characters, heightening the solemnity of the novella’s narrator. The tone turns most sentimental when George and Lennie discuss their plans to one day buy a farm together and settle on their own land, talking about the rabbits they will own and the beautiful things they will grow in their garden. The poetic tone of their dream not only contrasts with the harshness of their actual ranch-hand lives, but romanticizes the fraternal bond between these two companions who intend to stick together to the very end.