This article reviews the concept of cultural keystone species, or species that are central to the cultural identity and practices of a people. The authors find that the term ‘cultural keystone species’ has been inconsistently defined and rarely applied in conservation. Most documented cases come from North America and emphasize the species’ importance to people, rather than the reciprocal role people play in sustaining those species. The authors propose clearer definitions and emphasize the need to recognize the mutual relationship between species and cultural groups to better integrate this concept into biodiversity conservation.