The Diagnostic and Statistical Manual of Mental Disorders (DSM; latest edition: DSM-5-TR, published in March 2022) is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common language and standard criteria. It is the main book for the diagnosis and treatment of mental disorders in the United States and is considered one of the principle guides of psychiatry along with the ICD, CCMD and the Psychodynamic Diagnostic Manual.

It is used – mainly in the United States – by researchers, psychiatric drug regulation agencies, health insurance companies, pharmaceutical companies, the legal system, and policymakers. Mental health professionals use the manual to determine and help communicate a patient's diagnosis after an evaluation. Hospitals, clinics, and insurance companies in the United States may require a DSM diagnosis for all patients with mental disorders. Health-care researchers use the DSM to categorize patients for research purposes.

The DSM evolved from systems for collecting census and psychiatric hospital statistics, as well as from a United States Army manual. Revisions since its first publication in 1952 have incrementally added to the total number of mental disorders, while removing those no longer considered to be mental disorders.

Recent editions of the DSM have received praise for standardizing psychiatric diagnosis grounded in empirical evidence, as opposed to the theory-bound nosology (the branch of medical science that deals with the classification of diseases) used in DSM-III. However, it has also generated controversy and criticism, including ongoing questions concerning the reliability and validity of many diagnoses; the use of arbitrary dividing lines between mental illness and "normality"; possible cultural bias; and the medicalization of human distress.