The development and psychometric properties of the selective mutism questionnaire.

Research on selective mutism (SM) has been limited by the absence of standardized, psychometrically sound assessment measures. The purpose of our investigation was to present two studies that examined the factor structure and initial reliability and validity of the Selective Mutism Questionnaire (SMQ), a 17-item parent report measure of failure to speak related to SM. Study 1 (N = 589) utilized an Internet sample of parents of children ages 3 to 11 to demonstrate that the SMQ has a theoretically and clinically meaningful factor structure accounting for a significant portion of variance in responses with good internal consistency. Study 2 (N = 66) supported the validity of the SMQ in that scores discriminated clinic-referred children with SM from children with other anxiety disorders. Scores on the SMQ were correlated with measures of several theoretically and clinically important dimensions.