Those with SM experience anxiety related to speaking and sometimes they may also be unable to make eye contact, nod their heads, point or make other nonverbal forms of communication when in a social situation that provokes anxiety. SM may be an extreme form of social phobia. Social anxiety and avoidance characteristic of social phobia may be associated with SM, and thus, both diagnoses may be given. More than 90% of children with SM also meet the diagnostic criteria for social anxiety disorder, now termed social phobia (Black et al., 1996). Diagnosis of other comorbid anxiety disorders is also commonly diagnosed with SM and social phobia (Biedel & Turner, 1998). The name change from ‘elective’ to ‘selective mutism’ in DSM-IV deemphasized the oppositional behavior connotation that a child elected not to speak and rather emphasized the characteristic of the disorder, that there are select environments in which speaking does not occur (APA, 1994). Thus a child’s reluctance to speak and engage socially should not be interpreted as an oppositional behavior but as avoidance due to anxiety. The term ‘selective mutism is consistent with new etiological theories that focus on anxiety issues (Dow et al., 1995).

The current edition of the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision, or DSM-IV-TR (APA, 2000), states that the following criteria must be met in order to qualify for a diagnosis of selective mutism:

(a) An inability to speak in at least one specific social situation where speaking is expected (e.g., at school) despite speaking in other situations (e.g., at home);
(b) The disturbance has interfered with educational or occupational achievement or with social communication;
(c) The duration of the selective mutism is at least one month and is not limited to the first month of school;
(d) The inability to speak is not due to a lack of knowledge of or discomfort with the primary language required in the social situation; and,
(e) The disturbance cannot better be accounted for by a communication disorder (e.g. stuttering) and does not occur exclusively during the course of a pervasive developmental disorder, schizophrenia or other psychotic disorder.

A diagnosis of SM can only be made by a treating professional qualified to diagnose mental illness. While many parents and professionals unfamiliar with SM may identify many of the symptoms in their children, a formal diagnosis should be obtained to confirm that SM is present and not better accounted for by other disorders that also include the lack of speech as a presenting symptom.