ABSTRACT Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that is characterized by difficulties with social-communication and the presence of restricted and repetitive patterns of interest. It is well documented that children with ASD often experience co-occurring psychiatric difficulties, including anxiety. In fact, it is estimated that between 40 and 79% of children and adolescents with ASD experience at least one anxiety disorder. This range in prevalence is likely due to differences in study sample size and recruitment practices (e.g., community versus clinical samples), in the use of screening measures with reduced sensitivity to detect anxiety in ASD, in sample characteristics (e.g., child’s IQ, language skills), as well as differences in the presentation of anxiety in ASD. Anxiety disorders in youth with ASD can significantly interfere with functioning across school, home, and community settings, and anxiety related difficulties are thought to exacerbate core ASD symptoms, including increased avoidance and ritualistic/restricted behaviors. Within school settings specifically, anxiety may negatively impact class attendance and engagement, academic achievement, and peer relationships. Thus, learning more about anxiety difficulties at school can inform the development of school-based mental health interventions for students with ASD. Identifying anxiety within school settings can also facilitate appropriate selection of students with ASD experiencing anxiety, thereby fostering the academic and mental health functioning in these students.