The International Gambling Conference 2018 is themed ‘Flipping the iceberg on gambling harm, mental health and co-existing issues’. This theme has been chosen to reflect the complexities of gambling harm with the iceberg analogy used to portray how important it is to look at ‘what lies below the surface’ as well as what is presented on top. Gambling harms rarely occur in isolation. Rather, one of the key features of gambling problems is co-morbidity with a range of other harmful behaviours, environmental or situational factors, or poor mental health, such as alcohol use and depression. This poses challenges both from a clinical and public health perspective and we are hoping this conference theme will facilitate robust discussion on how we define gambling harm.