Once Upon a Cuento is an anthology of short stories by contemporary Latinx authors. The stories, written for young people, grade five and up, explore heritage and history, identity, language, and relationships from the perspective of Mexican-American, Cuban-American, Dominican-American, and Puerto Rican writers. In all, the collection features seventeen stories by well-known and emerging writers, most of which are original to this collection. Contributors include acclaimed Puerto Rican children's authors Nicholasa Mohr and Carmen T. Bernier-Grand; Cuban-American novelist, essayist, and poet Virgil Suárez; and Mexican-American short story writers and teachers Lorraine López and Sergio Troncoso.

The stories are grouped by theme—heritage, holidays, and contemporary culture; family life; friends and other relationships; and dealing with differences. Individual stories explore additional themes such as the challenge of making do with little money, the process of moving to a new country and learning English, and young people's relationships to animals and to the natural world. Each story contains an introduction that offers historical, cultural, and biographical information. A general introduction and list of works by the thirteen contributors offer further avenues for research and discussion.