The novel takes the form of a letter from Ramatoulaye to Aissatou, her childhood friend. Now middle-aged women, Ramatoulaye and Aissatou had gone to school together in French colonial Senegal. Both women had married young, and were able to choose husbands they loved rather than conform to the arranged marriage tradition. The friends have been separated for a long time, however, because Aissatou now lives in the United States while Ramatoulaye remained in Senegal. The reason Ramatoulaye decides to write is that her husband, Moudou, has recently died. Ramatoulaye is going through the mourning period with Binetou, her co-wife. When Moudou decided to take a second, much younger wife, Ramatoulaye chose to stay with him, in part because they had twelve children. She is writing to catch her friend up on the things that happened since she left for America.
Aissatou’s husband, Mawdo, had also decided to take a co-wife, a young relative that his aunt convinced his parents was more suited to the family’s elite status. Aissatou had decided at that time not to accept his decision; she divorced him and took their four sons. Although Ramatoulaye opted to stay in her marriage, her husband did not see things the same way. They remained married but, leaving her to care for the children, he left to live with his young bride. Ramatoulaye writes to her friend about how her understanding of life changed through the experience of providing for the family and further revelations that have come with widowhood. She has rejected offers from Moudou’s brother and a former suitor to become another co-wife. Her letter also brings Aissatou up to date with changes in Senegal society, as exemplified by the lives her grown children are living. Her son is a staunch nationalist; and one daughter’s marriage is one of equals, while another is pregnant but single and will finish her education before marrying.