Rates of aggression amongst people with intellectual disability (ID) have been found to be high in studies conducted on several continents across a number of service settings. Aggression is the primary reason for people with ID to be admitted or re-admitted to institutional settings, and it is also the main reason for individuals in this client group to be prescribed behaviour-control drugs. Anger is a significant activator of aggression, but little is known about the emotional aspects of the lives of people with ID. There are many reasons for this, but a lack of reliable and validated assessment measures is chief among them. The present review found that very little work has been conducted to date concerning the development of robust tools for assessing anger and aggression in this population. A narrative review of interventions for reducing aggression and anger in people with ID showed that there is virtually no evidence to support the use of psychotropic medications. Research has shown that behavioural interventions can be effective; however, they are intrusive and have not been tested in naturalistic settings with higher-functioning clients and low-frequency aggression. More recently, cognitive–behavioural interventions have shown promise, but the mechanisms for effective change have yet to be delineated. Priority research questions relating to assessment, treatment and therapeutic skills in working with anger and aggression problems are offered by the present review.