Although Sweetgrass is historical fiction, its storyline is one that is most familiar to contemporary readers, for it is simultaneously a love story and a coming-of-age story. At fifteen, Sweetgrass believes that she is more than old enough to marry Eagle Sun, someone with whom she has grown up. However, Sweetgrass's father, Shabby Bull, does not believe that she is ready to take on the demanding responsibilities of marriage, and Sweetgrass fears that her father will ignore her desire for a love marriage and will, instead, arrange a marriage for her with an old man, one who already has several wives. When Eagle Sun sends his older brother to meet with Shabby Bull regarding making a marriage match, Sweetgrass's father's response is that she is "not strong enough to be a sits-beside-him wife." To prove to her father that she actually is strong enough to marry, Sweetgrass must pass her father's test—to single-handedly prepare some thirty buffalo hides over the winter. However, a bigger test of a different type of strength confronts Sweetgrass during the winter when her siblings and almost- mother contract smallpox while Shabby Bull is away seeking food.