1) Selective mutism is a disorder where a person is unable to speak in certain social settings due to extreme anxiety and fear, such as at school, but is able to speak normally at home with family. 2) Symptoms include failure to speak in social situations, shyness, difficulty making eye contact, stiffness, worry, sensitivity to noise/crowds, and sleep problems. 3) Causes are believed to be social anxiety, genetics, brain differences like an overactive amygdala, and environmental factors like family stress or a misunderstanding of the disorder. With treatment including psychotherapy and speech therapy, children can often overcome selective mutism.