Autism spectrum disorders (ASDs), including Autistic Disorder, Asperger’s Disorder and Pervasive Developmental Disorder-Not Otherwise Speciﬁed (PDD-NOS), are characterized by impairments in social reciprocity and communication, together with repetitive and restricted behaviors and interests. In addition to these core symptoms, an estimated 40 % of children with ASDs fulﬁll diagnostic criteria for an anxiety disorder (van Steensel et al. 2011) and as many as 84 % have impairing, subclinical anxiety symptoms (White et al. 2009). Co-occurring anxiety can cause acute distress, amplify the core symptoms of ASD and trigger behavioral difﬁculties including tantrums, aggression and self-injury (Canitano 2006). Despite the prevalence of anxiety in ASDs, it remains unclear whether anxiety difﬁculties constitute a separate condition or align more closely with core ASD features.From Hallett V, Lecavalier L, Sukhodolsky DG, Cipriano N, Aman MG, McCracken JT, McDougle CJ, Tierney E, King BH, Hollander E, Sikich L, Bregman J,Anagnostou E, Donnelly C, Katsovich L, Dukes K, Vitiello B, Gadow K, Scahill L (2013). Exploring the manifestations of anxiety in children with autism spectrum disorders. J Autism Dev Disord.Oct;43(10):2341-52. doi: 10.1007/s10803-013-1775-1.