Diagnosis isn’t what it seems. It is usually treated as a label, arrived at by professionals, to explain a problem and to point to treatment. This view of diagnosis fits “the medical model”. Authors in this book view diagnosis as a process, not a label. Diagnosis involves a negotiation of power relationships as well as of professional accountability. The chapters reveal how today’s professionals and non-professionals use diagnosis to explain medical problems and also to explore how a diagnosis affects the identities of those diagnosed. In addition, some chapters show how diagnostic reasoning occurs in unexpected contexts such as when writing letters of recommendation and talking about communication. Together, a diverse array of authors from various backgrounds, highlight the many ways that diagnosis is deeply rooted in today’s culture.