The aim of this paper is to review studies available in scientific databases on the effectiveness of cognitive behavioral therapy programmes for separation anxiety disorder in children. The paper also includes a presentation of a clinical description of therapy for a 12-year-old girl with a diagnosis of separation anxiety according to ICD-10. The most widely researched and sole protocol for working with children with anxiety disorders in Poland, the Coping Cat programme, was used as the basic protocol. Its universality is both an advantage and a challenge, as it becomes necessary to adapt the protocol to work with a specific anxiety disorder. This required the authors of this article to review the scientific databases in search of examples of cognitive-behavioural protocol adaptations for treatment of separation anxiety in children. The case study describes the standard use of the Coping Cat protocol which, at some point, stopped delivering the desired results and needed to be modified based on analysis of the revisited conceptualisation together with the supervisor, which made it possible to achieve most of the assumed goals.