Selective mutism is one of the more severe anxiety disorders in children. It therefore takes some time for a child to learn to talk freely and spontaneously to everyone in all situations. Our experience shows that it takes approximately 12-24 months for selective mutism to resolve with an intensive treatment program. However, there are various factors that will impact on the rate of progress. These factors include the age of the child when they first present to treatment, the severity of the condition, the commitment of families and schools to implement the treatment program, and the existence of co-occurring anxieties or other behavioural problems. A child in preschool will often take less time than the above estimate (e.g., 6-12 months), and a child in high school will generally require longer treatment. If a child also has Autism or other severe anxiety disorders, then treatment tends to take longer.