Dialect is very important in the novel. Lee uses dialect in To Kill a Mockingbird in order to give the reader a sense of the way the people in Maycomb talked. Dialect is used to denote class in the South. Many people who use the Southern dialect are stereotypically considered ignorant and uneducated. The Ewells of Maycomb fit into this category, and they predominantly use the Southern dialect. They seldom use the final "g" at the end of gerunds, and the word "ain't" appears quite often in their speech. Atticus Finch, while a member of the Maycomb community, uses standard English, thus denoting his level of education. Scout's use of the Southern vernacular, though she lives in the house with Atticus, may lead the reader to infer that she is influenced heavily by her peer group at school and in the community. Even Tom Robinson's dialect, with the lack of an "r" sound at the end of some words, demonstrates how people believed African Americans in the South talked during that time period.

Lee's use of dialect can be compared to other works based in the South from that time period, such as Gone with the Wind. By using the Southern patterns of speech in her novel, Lee gave the reader a sense of being "there" and thus created one of the most powerful novels of her generation.

The story takes place in Maycomb County, Alabama. In the South, particularly at the time during which this story is set—the 1930s—people spoke with a distinct Southern dialect. The narrative reflects this by leaving the "g" off of gerunds when the characters speak and includes vocabulary, such as "reckon," which was more commonly used by people in this region.

For this story, the Southern dialect is necessary to evoke the setting and to establish authenticity. Lee wanted the readers to believe that they were reading conversations between Southerners. On the other hand, the story is narrated by the adult Scout who does not speak with a conventional "Southern" voice but instead in standard American English. When she narrates, the "g" is replaced on gerunds, and Southern slang disappears in favor of more formal language.