The relationship between selective mutism (SM) and childhood anxiety disorders is illustrated through an examination of their temperamental, environmental, and biological etiologies. SM is also explored as a symptom of the specific anxiety disorders of social phobia, separation anxiety, and posttraumatic stress disorder. The etiology and symptom overlap demonstrates SM as being an anxiety disorder or a variant of a specific anxiety disorder. The conceptualization of SM as an anxiety disorder is helpful in effectively treating afflicted children. There is enough evidence in the current literature to challenge the current classification, from the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders of SM as an Other Disorder of Infancy, Childhood, and Adolescence.