This report provides a conceptual summary and critique of problem and pathological gambling and how these terms are used in policy, research and clinical practice. It summarises the varying disciplinary approaches to understanding gambling-related disorders; the distinction drawn between harm and behavioural indicators; issues in measurement; and, the significance of longitudinal evidence relating to the stability of gambling-related problems. "Pathological gambling" is identified as the principal term used in psychiatric (e.g., DSM-IV) or medical literature and one which is defined largely in terms of the mechanisms which are central to substance use disorders (cravings, tolerance and withdrawal). By contrast, "problem gambling" appears to have to two common usages. In one usage, problem gambling refers to a less severe form of the disorder; in another, it refers to a public health conceptualisation that defines the disorder largely in terms of its harmful consequences. Commonly used psychometric measures of the disorder vary in relation to which of these conceptualisations is captured, but most include items relating to both behavioural indicators of pathology as well as harmful impacts. Longitudinal evidence suggests that reported problem gambling symptoms are often not stable over time. Individuals commonly shift between categories and this suggests that gambling-related disorders are unlikely (at least in some individuals) to be solely determined by underlying neurophysiological and dispositional factors that are immutable over time. The report supports the view that the causes of problem and pathological gambling are likely to be multi-faceted and require multi-disciplinary approaches to understand the factors responsible for the development of the disorder as well as its maintenance.