The novel is written in a third-person narrative. Green used third person to create empathy for Colin. In a blog post, Green wrote that the novel "needed to be written in third person, because it's about a guy whose brain does not lend itself to narratives, and who struggles to tell stories in ways other people find interesting."
The story includes many footnotes that become an essential part to understanding Colin's brain and how it works. Green says that the footnotes "function as a kind of competing narrative that comments upon and—for lack of a better word—problematizes the central narrative." An Abundance of Katherines is a fiction work that includes many mathematical terms and academic language. With the footnotes and The Appendix that is at the end of the novel, Green gives his readers "a way of attempting to achieve precision and clarity" of the story in general, but more specifically, Colin's mind.
The book consists of 19 chapters to highlight the number 19. These chapters include Colin's flashbacks, which are "meant to reflect the relationship we have between chronological narrative and emotional narrative." This format is also known as non-linear narrative.