This review systematically examined the literature on the ability of adults with an intellectual disability (ID) to recognise facial expressions of emotion. Studies were included that: recruited only adult participants with ID; that did not specifically recruit participants with co-morbid diagnoses of syndrome(s) related to ID; and that directly compared the performance of adults with ID with a group of people without ID. Nine papers met the eligibility criteria for review and were assessed against pre-defined quality rating criteria and the findings synthesised. The majority of included studies were assessed as being of acceptable overall methodological quality. All of the studies reported a relative impairment in emotion recognition for participants with ID on at least some of the tasks administered, with a large effect size being found for most of the significant results. The review suggests that adults with ID are relatively impaired in recognising facial expressions of emotion, when compared with either adults or children without ID. Methodological variation between studies limits the extent to which any interpretations can be made as to the cause of impaired emotion recognition in adults with ID.