Yerma is the story of a childless woman living in rural Spain who desperately desires motherhood. Her husband is a frugal, economically driven man who has no desire to have children. For him, children are a costly transaction. Yerma's obsession with motherhood drives her to commit a horrific crime. Her desperation is produced by the social norms of her culture, and the play "Yerma" functions as a critique of those norms.
Yerma is part of Lorca's "rural trilogy," three plays that emphasize the submissive position of women who desire freedom in a traditional society which denies them social or sexual equality.