Improving mental health is a national priority in Scotland. NHS Health Scotland was commissioned by the Scottish Government to establish a core set of sustainable mental health indicators to enable national monitoring. This report provides the first ever systematic assessment of the adult population’s overall mental health. The report has three objectives: to provide a description of the state of mental health and the associated contextual factors that influence it at a single point in time, using the most recent available data, to analyse time trends for each indicator over the last decade, where possible, and to identify differences within the adult population by selected dimensions of equality, where possible.