While a plethora of cognitive behavioral empirically supported treatments (ESTs) are available for treating child and adolescent anxiety and depressive disorders, research has shown that these are not as effective when implemented in routine practice settings. Research is now indicating that is partly due to ineffective EST training methods, resulting in a lack of therapist competence. However, at present, the specific competencies that are required for the effective implementation of ESTs for this population are unknown, making the development of more effective EST training difficult. This study therefore aimed to develop a model of therapist competencies for the empirically supported cognitive behavioral treatment of child and adolescent anxiety and depressive disorders using a version of the well-established Delphi technique. In doing so, the authors: (1) identified and reviewed cognitive behavioral ESTs for child and adolescent anxiety and depressive disorders, (2) extracted therapist competencies required to implement each treatment effectively, (3) validated these competency lists with EST authors, (4) consulted with a panel of relevant local experts to generate an overall model of therapist competence for the empirically supported cognitive behavioral treatment of child and adolescent anxiety and depressive disorders, and (5) validated the overall model with EST manual authors and relevant international experts. The resultant model offers an empirically derived set of competencies necessary for effectively treating children and adolescents with anxiety and depressive disorders and has wide implications for the development of therapist training, competence assessment measures, and evidence-based practice guidelines for working with this population. This model thus brings us one step closer to bridging the gap between science and practice when treating child and adolescent anxiety and depression.