• anxiety disorders;
  • autism spectrum disorder in youth;
  • psychometric theory;
  • test validation process

In this brief commentary, we reflect on two issues attendant to the comprehensive review of anxiety in youth with autism spectrum disorder (ASD) by Kerns and Kendall (2012). Specifically, we explore (a) issues related to unique and shared features of anxiety in youth with ASD and neurotypical youth and (b) the meaning of validation in psychological research. We conclude that anxiety in youth with ASD is characterized by a set of unique features that must be considered in assessing anxiety in these youth and that test instruments must attend to various aspects of a complex validation process. We conclude that validation is not a condition of an instrument per se but an ongoing, iterative process.