Background: Many authors have expressed concern regarding the efficacy of psychotherapy, including psychotherapy for people with intellectual disabilities. Materials and Methods: Recently, many authors have made claims for the effectiveness of cognitive therapy for treating people with intellectual disabilities. During this debate, applied behaviour analysis has been misrepresented by incorrectly labelling behavioural as cognitive techniques, repeated misrepresentations of behaviourism and attributing the efficacy of treatment packages to cognitive components of undemonstrated efficacy when it is more parsimonious to attribute efficacy to behavioural elements of known efficacy. Conclusions: This article documents and corrects these errors.