Cognitive Behavioural Therapy (CBT) is a psychological therapy with an evidence base in treating neurotypical adults and children with various mental health problems. CBT has been applied to individuals with high-functioning autism spectrum disorder in individual and group settings for the treatment of comorbid mental health difficulties (e.g. anxiety) and core autism-related difficulties (e.g. social understanding). This paper briefly describes the literature and considers the specific challenges of applying CBT to this population. It also describes a range of modifications to CBT that need to be made in adapting the treatment for the patient group, including taking a more directive approach, ensuring an increased use of written/visual material, a greater emphasis on affective education, avoidance of metaphor/abstract concepts, the incorporation of special interests and the involvement of family members.