This article discusses the social organization of psychiatric work in the psychiatric emergency department of a public general hospital located in New York City, based on ethnographic research conducted from 1999 to 2001. Case studies of the care of two patients with ambiguous symptoms are discussed. The analysis applies the ‘‘differences approach’’ developed by Mol and colleagues which focuses on the way different professions provide divergent explanations and ontologies for symptoms and illness. The cases illustrate the ways in which social structural constraints are compelling psychiatry to become a multidisciplinary specialty.