Background: Cognitive behavioural therapy (CBT) is being increasingly adapted for use with people who have an intellectual disability. However, it remains unclear whether inherent cognitive deficits that are present in adults who have an intellectual disability preclude the use of cognitive-based therapies. This review aims to systematically examine "cognitive therapy skills" in adults who have an intellectual disability that assist engagement in CBT. Method: Two authors independently reviewed titles and abstracts of articles located through electronic database searching. Results: Outcomes of the 18 studies selected for full-text review are mixed and limited by a moderately high risk of bias. Conclusions: The authors suggest eleven findings from research areas of emotion recognition, cognitive mediation, discriminating between thoughts, feelings and behaviours, linking events and emotions that have implications for the design of CBT programmes and future research for this population.