Although Gaines often pauses the narrative of A Lesson Before Dying to explain the harsh realities of segregation, he rarely gives such explication of Cajun culture, which may be unfamiliar to most readers. Nevertheless, the Cajun backdrop is an important element of the novel, and helps to explain how the characters behave. The Cajuns are a discrete ethnic group, primarily in Louisiana, who are the modern descendants of the Acadians, who were expelled from Nova Scotia in the nineteenth century by the British monarchy, which then ruled Canada.
Cajun pronunciation and slang is used by many characters in the novel, despite the fact that most of them identify with African-American rather than Cajun culture. Examples of this include Jefferson's name for Miss Emma, Nannan, and Grant and Vivian's habit of speaking to each other in Cajun-inflected French. The Roman Catholic Cajuns also influence the religious atmosphere in which the novel takes place. Especially in the early- to mid-twentieth century, some Cajun Catholics had an aversion to Protestantism. This can be traced back to the Great Expulsion, when the Cajuns were forced to leave Canada. This atmosphere of religious strife helps to explain the tension when Tante Lou finds out that Vivian is Catholic. It also helps explain the defensiveness of Reverend Ambrose around the agnostic Grant, even though Reverend Ambrose is Protestant.
Cajun identity remains a defining element of Louisiana culture, and recent developments for the group would have been in the news as Gaines was writing A Lesson Before Dying. In 1980, a discrimination lawsuit was filed that ultimately allowed Cajuns to be recognized as an official ethnic group by the U.S. government. The group's concern about whether it can continue to be cohesive in coming decades certainly parallels Grant's concerns that African-American culture is being eroded. In recent years, concerns about the decline of Cajun culture have become even more grave. Commercial fishing, an economic pillar of the community, has become less profitable due to climate change, international competition, and recently, the Deepwater Horizon oil spill in 2010. This has led some young Cajuns to seek jobs outside of the community and even in other parts of the country.