Selective mutism is a social anxiety condition, in which a person who is quite capable of speech, is unable to speak in given situations.
The disorder can also be the result of trauma experienced, especially at an early age, which gives such a shock and results in refusing to speak, which can then later lead to shyness of speaking especially if the child missed out on years of speech development.
More on [ Selective mutism ]
Child and Adolescent :: Mental Health

Selective Mutism Foundation Official Website - Information about this childhood anxiety disorder and the foundation itself. Includes resources, research and a list of healthcare providers.
Selective Mutism Group Inc - Includes information, professional QA, a forum for parents, professionals and teachers to discuss the problem, and current research.
Meta Description: [ Selective Mutism is a childhood anxiety disorder, more than just shyness
but not refusal to speak ]
The Quiet Room - An informational resource for parents and professionals dealing with children with the disorder.
The Silence Within - A teacher and parent resource for strategies to use with shy children and those with selective mutism.
Yahoo Groups : Selectivemutism - An e-mail discussion and support group focused on this disorder.
Meta Description: [ selectivemutism: SelectiveMutism ]