Harper Lee establishes a humorous tone at the very start of the novel To Kill a Mockingbird by creating a narrator who has a very strong sense of humor. Scout, the narrator, expresses her sense of humor within the very first page of the novel. The adult Scout opens the novel by reflecting back on a time when Jem's arm was broken. She expresses that she and Jem have a difference of opinion concerning the events that led up to the incident. Scout believes that the "Ewells started it all"; Jem maintains that he and Dill started it all by trying to make Arthur (Boo) Radley come out of his house. Scout's sense of humor is very clearly established in her following narrated reply to her brother:

I said if he wanted to take a broad view of the thing, it really began with Andrew Jackson. If General Jackson hadn't run the Creeks up the creek, Simon Finch would never have paddled up the Alabama, and where would we be if he hadn't? (Ch. 1)

Through this reply, Scout is humorously asserting that the establishment of the Finch family in Alabama can be traced all the way back to Andrew Jackson, who cleared Alabama of the Creek Indian tribe; therefore, any event that happens within the Finch family can be traced to the actions of Andrew Jackson. This is a humorous notion because, of course, it's a bit ridiculous to trace events leading up to Jem's arm being broken all the way back to the actions of Andrew Jackson. Scout continues to use this same humorous voice throughout the novel as she continues to narrate.

Author Lee also makes use of irony to develop humor in the story, especially verbal irony. Verbal irony is created when a speaker or writer uses words to mean the exact opposite of what is literally being said. Professor Lyman A. Baker gives us the following example of verbal irony in a comment given by a mother to her son about his television viewing:

Don't let me tempt you from your duties, kiddo, but when you're finished with your serious studies there, maybe we could take some time out for recreation and do a little math. ("Critical Concepts: Verbal Irony," Kansas State University)

Here, the mother is using the phrase "serious studies" to refer to watching television and the word "recreation" to refer to doing math homework, but she actually means the exact opposite of what she is saying. She is really telling her son to stop wasting recreational time watching television and start doing his serious homework.

In To Kill a Mockingbird, we see one example of Scout the narrator using verbal irony when reflecting on her dealings with her first-grade teacher, Miss Caroline, on her very first day of school. Miss Caroline is absolutely shocked to discover that Scout already knows how to read and well above her grade level. Miss Caroline assumes that Scout's father taught her to read and commands her to tell her father to stop teaching her because he "doesn't know how to teach" (Ch. 2). Yet, Scout says no one taught her to read, and she can't really remember a time when she couldn't read--it has just come to her naturally. Scout uses verbal irony to inform her reader of her shock and disappointment to discover that her teacher would consider her reading abilities a bad thing:

I mumbled that I was sorry and retired meditating upon my crime. I never deliberately learned to read, but somehow I had been wallowing illicitly in the daily papers. (Ch. 2)

In this passage, Scout uses the word "crime" ironically. Literally, the word crime is used to speak of any activities that are immoral or dangerous to public welfare; however, Scout is using it to mean the exact opposite--knowing how to read at an early age should not be considered a crime but rather a benefit to society. Scout further uses the word "illicitly" ironically. The word illicit refers to any activities that are not permitted by authorities or unlawful. But, Scout is using "illicitly" to say that reading is absolutely not a criminal activity but rather an activity beneficial to society.

Verbal irony can help produce humor because saying the exact opposite of what one means can produce a comic effect, as we see from the examples above.

Throughout To Kill a Mockingbird, the narrator (the adult Jean Louise Finch) continually includes information about her younger self—nicknamed Scout—to remind the reader that she is speaking from a vantage point years later than the events in the novel.

These references often include Scout's use of language that she did not quite understand (but which the adult narrator assumes that the reader will). The result is often humorous, and the irony results from that gap in comprehension. One clear case is Scout's use of "morphrodite" (meaning "hermaphrodite") after she overhears Miss Maudie speaking about the combined male and female attire on the chidren's "snowman."

One example of skillful repetition comes in Scout's description of summer, in which the structure "it was . . ." is repeated, with different examples of what the season represented—culminating in her appreciation of her friend Dill.

Throughout Robinson's trial, people (including the witnesses) use many euphemisms for rape; Sheriff Tate, for example, testifies that Mayella told him that Robinson "took advantage of her." Allusions, both correctly and incorrectly used, abound. These include the Rosetta Stone, to which Mr. Avery refers to as a code of conduct rather than a multi-lingual text; there are also numerous allusions to Civil War conflicts and leaders such as the Battle of Appamatox and Stonewall Jackson.