With the adoption of a developmental psychopathology perspective, the DSM-5 translates empirical evidence on the continuity of childhood anxiety disorders into diagnostic practice, thereby completing a process that started with the exclusion of the former childhood anxiety disorders overanxious disorder and avoidant disorder from DSM-III to DSM-IV. This change in perspective, however, leads to a low level of concordance between the DSM-5 and ICD-10. To reliably identify anxiety disorders at different points in development, and to take into account their developmental pathways, assessment instruments need to be sensitive to age-related manifestations and age-related subtypes of a disorder. This may best be achieved by a multi-informant, multi-method assessment approach. With regard to treatment, only cognitive-behavioral therapy (CBT) fulfills the criteria of an evidence-based treatment approach in youth. Disorder-specific treatments can lead to larger treatment effects and slightly higher remission rates as compared to more general treatment programs for childhood anxiety disorders (e.g., Coping Cat). Parental involvement seems not to add to treatment success. In conclusion, the evidence-based diagnostic approach of the DSM-5 needs to be complemented by the development and evaluation of child-friendly, developmentally sensitive assessment tools and evidence-based treatments for anxiety disorders in children. With regard to diagnostic concordance, the gap between the DSM-5 and ICD-10 needs to be bridged by more closely aligning the two nosological systems.