Prevalence estimates for SM range between 0.2% - 1.6%. SM Prevalence may be higher in immigrant children, individuals in a language-minority group, or individuals with speech/language delays. SM often occurs between ages 3-6, while diagnosis for this disorder often occurs during ages 5-8 -- about the time children enter school.

Note that there is currently a lack of consensus regarding the population estimates of SM, as they are difficult to ascertain; this data has been gathered via various different diagnostic criteria and population samples which have been compared to one another. Additionally, there is no consensus on the relation between SM prevalence and gender assigned at birth. While most studies report that it affects females more than males, some studies find that it affects more males than females, or that there seems to be no difference by gender.

Definitions:

The INCIDENCE of Selective Mutism refers to the number of new cases identified in a specific time period.

The PREVALENCE of Selective Mutism refers to the number of individuals who are living with Selective Mutism in a current time period.