The play’s speaking lines are almost exclusively written in what is called African American Vernacular English (AAVE). This is a term for a prominent dialect used by many Black Americans—a dialect scholars have long recognized as having a specific set of vocabulary, grammar, and pronunciation rules. Writing the play in AAVE is foundational to the play as a work of social realism, informing the portrayal Black Americans and their struggle.
Hansberry takes great care to describe how her characters sound. When describing Mama Younger, for instance, she writes, "Her speech, on the other hand, is as careless as her carriage is precise—she is inclined to slur everything—but her voice is perhaps not so much quiet as simply soft." Hansberry specifically describes the dialect of her characters as a product of Chicago’s South Side: she writes of Beneatha: “Her speech is a mixture of many things; it is different from the rest of the family’s insofar as education has permeated her sense of English [...] but not altogether, because over all of it is a soft slurring and transformed use of vowels which is the decided influence of the Southside.” The reader can then imagine the soft slurring and transformed use of vowels as characterizing the family’s dialect, an aspect of the play one would almost certainly have heard if attending a performance as opposed to reading it on paper.
Nevertheless, Hansberry’s writing communicates the dialect through the written word and not just stage directions. Her commitment to writing the character’s lines in AAVE sharply juxtaposes that which is meant to be spoken aloud against her stage directions, two entirely distinct dictions that make the reader's experience as similar to actually viewing the play as possible.