Abstract This commentary responds to several patterns in the articles that constitute the special issue on “Diagnosing America” and underscores questions of legitimacy related to the history of psychiatric diagnoses. Clinical diagnosis often operates as a speech-act through which a patient’s distress is made recognizable and legitimated. However, diagnostic categories have long been plagued by questions of legitimacy from within and beyond the field of psychiatry. Despite attempts to resolve these controversies through successive editions of the Diagnostic and Statistical Manual of Mental Disorders (DSM), concerns about the validity and reliability of diagnostic categories persist. The stakes of such questions are significant. Diagnostic categories may not only describe but can also shape historically shifting expressions of mental illness and their treatments. Many works of contemporary literature have engaged in these debates by foregrounding the social, political, and phenomenological dimensions of mental illness that have often been absent from diagnostic and therapeutic procedures. Such works prompt fundamental questions about how and why certain categories of mental illness come to be recognized as real. Discussions of the cultural and social dimensions of psychiatric diagnosis should include . . . questions of legitimacy—not of patients’ distress but of the nosological systems that purport to recognize forms of distress as real according to the historically prevailing ontology.