The American Psychiatric Association (APA) is the main professional organization of psychiatrists and trainee psychiatrists in the United States, and the largest psychiatric organization in the world. Its some 36,000 members are mainly American but some are international. The association publishes various journals and pamphlets, as well as the Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM codifies psychiatric conditions and is used worldwide as a key guide for diagnosing disorders. The organization has its headquarters in Arlington County, Virginia.