Purpose – The Donner expedition to California in 1846‐1847 is one of the darkest tales of the great migrations west. While much has been written about the tragedy, a group analysis based on business research has not been undertaken. The purpose of this paper is to suggest that the story of the Donner Party is primarily a group failure, with implications for practicing managers employing temporary groups in uncertain situations.Design/methodology/approach – Group theories concerning the nature of temporary work groups, interdependence, diversity, social identity, and leadership are employed to explain how negative group processes likely contributed to the disaster.Findings – Based on books and a film about the incident, the Donner Party suffered a social breakdown based on: the changing nature of the goals of the expedition in mid‐course, which is difficult for temporary teams to handle; destructive forms of diversity based on cultural background and social status; and a lack of critical skills and effecti...