The concept of ‘addiction’ has long been used with reference to substance use disorders. There has, however, been growing interest in applying the term to other conditions, i.e. behavioural addictions, which are characterized by preoccupation with and decreased control over a range of behaviours other than substance intake that are rewarding but have adverse consequences. The best studied behavioural addiction, gambling disorder, is now included in DSM-5 under the rubric of substance-related and addictive disorders. In contrast, an ICD-11 proposal argues that pathological gambling continues to be classified as an impulse control disorder. Other putative behavioural addictions, such as compulsive sexual behaviour and internet gaming addiction, are equally controversial. Here, we review some of the relevant debates. We argue that while the construct of behavioural addiction may be useful in clinical practice and in research contexts, further work is needed to assess the extent of its diagnostic validity and clinical utility.